Merge branch 'danielsilverstone-ct/fix-lint-issues' into 'master'

Fix lint issues

See merge request BuildStream/buildstream!892

30 files changed, 91 insertions, 91 deletions

diff --git a/.gitignore b/.gitignore
index fae0f4eea..8c72c4f3f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -34,3 +34,4 @@ doc/source/modules.rst
 doc/source/buildstream.rst
 doc/source/buildstream.*.rst
 doc/build/
+versioneer.pyc
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 07fa859d8..02a803de4 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -1,4 +1,4 @@
-image: buildstream/testsuite-debian:9-master-114-4cab18e3
+image: buildstream/testsuite-debian:9-master-119-552f5fc6
 
 cache:
   key: "$CI_JOB_NAME-"
@@ -78,7 +78,7 @@ source_dist:
   # Go back to the toplevel and collect our reports
   - cd ../..
   - mkdir -p coverage-linux/
-  - cp dist/buildstream/.coverage.* coverage-linux/coverage."${CI_JOB_NAME}"
+  - cp dist/buildstream/.coverage coverage-linux/coverage."${CI_JOB_NAME}"
   except:
   - schedules
   artifacts:
@@ -86,25 +86,25 @@ source_dist:
     - coverage-linux/
 
 tests-debian-9:
-  image: buildstream/testsuite-debian:9-master-117-aa3a33b3
+  image: buildstream/testsuite-debian:9-master-119-552f5fc6
   <<: *linux-tests
 
 tests-fedora-27:
-  image: buildstream/testsuite-fedora:27-master-117-aa3a33b3
+  image: buildstream/testsuite-fedora:27-master-119-552f5fc6
   <<: *linux-tests
 
 tests-fedora-28:
-  image: buildstream/testsuite-fedora:28-master-117-aa3a33b3
+  image: buildstream/testsuite-fedora:28-master-119-552f5fc6
   <<: *linux-tests
 
 tests-ubuntu-18.04:
-  image: buildstream/testsuite-ubuntu:18.04-master-117-aa3a33b3
+  image: buildstream/testsuite-ubuntu:18.04-master-119-552f5fc6
   <<: *linux-tests
 
 tests-unix:
   # Use fedora here, to a) run a test on fedora and b) ensure that we
   # can get rid of ostree - this is not possible with debian-8
-  image: buildstream/testsuite-fedora:27-master-117-aa3a33b3
+  image: buildstream/testsuite-fedora:27-master-119-552f5fc6
   stage: test
   variables:
     BST_FORCE_BACKEND: "unix"
@@ -128,7 +128,7 @@ tests-unix:
     # Go back to the toplevel and collect our reports
     - cd ../..
     - mkdir -p coverage-unix/
-    - cp dist/buildstream/.coverage.* coverage-unix/coverage.unix
+    - cp dist/buildstream/.coverage coverage-unix/coverage.unix
   except:
   - schedules
   artifacts:
diff --git a/MANIFEST.in b/MANIFEST.in
index 9c16ce051..5c001616a 100644
--- a/MANIFEST.in
+++ b/MANIFEST.in
@@ -8,19 +8,27 @@ include README.rst
 
 # Documentation package includes
 include doc/Makefile
+include doc/badges.py
+include doc/bst2html.py
 include doc/source/conf.py
-include doc/source/index.rst
+include doc/source/plugin.rsttemplate
+recursive-include doc/source *.rst
+recursive-include doc/source *.py
+recursive-include doc/source *.in
+recursive-include doc/source *.html
+recursive-include doc/examples *
 
 # Tests
-recursive-include tests *.py
-recursive-include tests *.yaml
-recursive-include tests *.bst
-recursive-include tests *.conf
-recursive-include tests *.sh
-recursive-include tests *.expected
+recursive-include tests *
+include conftest.py
+include .coveragerc
+include .pylintrc
 
 # Protocol Buffers
 recursive-include buildstream/_protos *.proto
 
 # Requirements files
 include dev-requirements.txt
+
+# Versioneer
+include versioneer.py
diff --git a/buildstream/_artifactcache/artifactcache.py b/buildstream/_artifactcache/artifactcache.py
index 5e698babb..8ea6c9dc2 100644
--- a/buildstream/_artifactcache/artifactcache.py
+++ b/buildstream/_artifactcache/artifactcache.py
@@ -156,7 +156,7 @@ class ArtifactCache():
     def setup_remotes(self, *, use_config=False, remote_url=None):
 
         # Ensure we do not double-initialise since this can be expensive
-        assert(not self._remotes_setup)
+        assert not self._remotes_setup
         self._remotes_setup = True
 
         # Initialize remote artifact caches. We allow the commandline to override
@@ -252,7 +252,7 @@ class ArtifactCache():
     #    (int): The size of the cache after having cleaned up
     #
     def clean(self):
-        artifacts = self.list_artifacts()
+        artifacts = self.list_artifacts()  # pylint: disable=assignment-from-no-return
 
         # Build a set of the cache keys which are required
         # based on the required elements at cleanup time
@@ -294,7 +294,7 @@ class ArtifactCache():
             if key not in required_artifacts:
 
                 # Remove the actual artifact, if it's not required.
-                size = self.remove(to_remove)
+                size = self.remove(to_remove)  # pylint: disable=assignment-from-no-return
 
                 # Remove the size from the removed size
                 self.set_cache_size(self._cache_size - size)
@@ -311,7 +311,7 @@ class ArtifactCache():
     #    (int): The size of the artifact cache.
     #
     def compute_cache_size(self):
-        self._cache_size = self.calculate_cache_size()
+        self._cache_size = self.calculate_cache_size()  # pylint: disable=assignment-from-no-return
 
         return self._cache_size
 
diff --git a/buildstream/_artifactcache/cascache.py b/buildstream/_artifactcache/cascache.py
index 2454366ac..b99f4d7b8 100644
--- a/buildstream/_artifactcache/cascache.py
+++ b/buildstream/_artifactcache/cascache.py
@@ -33,11 +33,11 @@ import grpc
 
 from .. import _yaml
 
+from .._protos.google.rpc import code_pb2
 from .._protos.google.bytestream import bytestream_pb2, bytestream_pb2_grpc
 from .._protos.build.bazel.remote.execution.v2 import remote_execution_pb2, remote_execution_pb2_grpc
 from .._protos.buildstream.v2 import buildstream_pb2, buildstream_pb2_grpc
 
-from .._message import MessageType, Message
 from .. import _signals, utils
 from .._exceptions import ArtifactError
 
@@ -81,8 +81,9 @@ class CASCache(ArtifactCache):
     ################################################
 
     def preflight(self):
-        if (not os.path.isdir(os.path.join(self.casdir, 'refs', 'heads')) or
-            not os.path.isdir(os.path.join(self.casdir, 'objects'))):
+        headdir = os.path.join(self.casdir, 'refs', 'heads')
+        objdir = os.path.join(self.casdir, 'objects')
+        if not (os.path.isdir(headdir) and os.path.isdir(objdir)):
             raise ArtifactError("CAS repository check failed for '{}'"
                                 .format(self.casdir))
 
@@ -918,7 +919,7 @@ class CASCache(ArtifactCache):
             # Skip download, already in local cache.
             pass
         elif (digest.size_bytes >= remote.max_batch_total_size_bytes or
-                not remote.batch_read_supported):
+              not remote.batch_read_supported):
             # Too large for batch request, download in independent request.
             self._ensure_blob(remote, digest)
             in_local_cache = True
@@ -958,7 +959,7 @@ class CASCache(ArtifactCache):
         batch = _CASBatchRead(remote)
 
         while len(fetch_queue) + len(fetch_next_queue) > 0:
-            if len(fetch_queue) == 0:
+            if not fetch_queue:
                 batch = self._fetch_directory_batch(remote, batch, fetch_queue, fetch_next_queue)
 
             dir_digest = fetch_queue.pop(0)
@@ -1087,6 +1088,10 @@ class _CASRemote():
         self.bytestream = None
         self.cas = None
         self.ref_storage = None
+        self.batch_update_supported = None
+        self.batch_read_supported = None
+        self.capabilities = None
+        self.max_batch_total_size_bytes = None
 
     def init(self):
         if not self._initialized:
@@ -1191,13 +1196,13 @@ class _CASBatchRead():
         assert not self._sent
         self._sent = True
 
-        if len(self._request.digests) == 0:
+        if not self._request.digests:
             return
 
         batch_response = self._remote.cas.BatchReadBlobs(self._request)
 
         for response in batch_response.responses:
-            if response.status.code != grpc.StatusCode.OK.value[0]:
+            if response.status.code != code_pb2.OK:
                 raise ArtifactError("Failed to download blob {}: {}".format(
                     response.digest.hash, response.status.code))
             if response.digest.size_bytes != len(response.data):
@@ -1236,13 +1241,13 @@ class _CASBatchUpdate():
         assert not self._sent
         self._sent = True
 
-        if len(self._request.requests) == 0:
+        if not self._request.requests:
             return
 
         batch_response = self._remote.cas.BatchUpdateBlobs(self._request)
 
         for response in batch_response.responses:
-            if response.status.code != grpc.StatusCode.OK.value[0]:
+            if response.status.code != code_pb2.OK:
                 raise ArtifactError("Failed to upload blob {}: {}".format(
                     response.digest.hash, response.status.code))
 
diff --git a/buildstream/_context.py b/buildstream/_context.py
index d2086af93..e3c290b7b 100644
--- a/buildstream/_context.py
+++ b/buildstream/_context.py
@@ -364,7 +364,6 @@ class Context():
         assert self._message_handler
 
         self._message_handler(message, context=self)
-        return
 
     # silence()
     #
diff --git a/buildstream/_frontend/app.py b/buildstream/_frontend/app.py
index f3dcd623b..eeb5f3eb2 100644
--- a/buildstream/_frontend/app.py
+++ b/buildstream/_frontend/app.py
@@ -20,7 +20,6 @@
 from contextlib import contextmanager
 import os
 import sys
-import resource
 import traceback
 import datetime
 from textwrap import TextWrapper
diff --git a/buildstream/_frontend/status.py b/buildstream/_frontend/status.py
index fd1a5acf1..2e7213e78 100644
--- a/buildstream/_frontend/status.py
+++ b/buildstream/_frontend/status.py
@@ -18,8 +18,8 @@
 #        Tristan Van Berkom <tristan.vanberkom@codethink.co.uk>
 import os
 import sys
-import click
 import curses
+import click
 
 # Import a widget internal for formatting time codes
 from .widget import TimeCode
diff --git a/buildstream/_fuse/hardlinks.py b/buildstream/_fuse/hardlinks.py
index 0797cb4bc..ff2e81eea 100644
--- a/buildstream/_fuse/hardlinks.py
+++ b/buildstream/_fuse/hardlinks.py
@@ -42,9 +42,11 @@ from .mount import Mount
 #
 class SafeHardlinks(Mount):
 
-    def __init__(self, directory, tempdir, fuse_mount_options={}):
+    def __init__(self, directory, tempdir, fuse_mount_options=None):
         self.directory = directory
         self.tempdir = tempdir
+        if fuse_mount_options is None:
+            fuse_mount_options = {}
         super().__init__(fuse_mount_options=fuse_mount_options)
 
     def create_operations(self):
diff --git a/buildstream/_fuse/mount.py b/buildstream/_fuse/mount.py
index 83c98a97a..e31684100 100644
--- a/buildstream/_fuse/mount.py
+++ b/buildstream/_fuse/mount.py
@@ -87,8 +87,8 @@ class Mount():
     #               User Facing API                #
     ################################################
 
-    def __init__(self, fuse_mount_options={}):
-        self._fuse_mount_options = fuse_mount_options
+    def __init__(self, fuse_mount_options=None):
+        self._fuse_mount_options = {} if fuse_mount_options is None else fuse_mount_options
 
     # mount():
     #
@@ -182,7 +182,7 @@ class Mount():
 
         # Ask the subclass to give us an Operations object
         #
-        self.__operations = self.create_operations()
+        self.__operations = self.create_operations()  # pylint: disable=assignment-from-no-return
 
         # Run fuse in foreground in this child process, internally libfuse
         # will handle SIGTERM and gracefully exit its own little main loop.
diff --git a/buildstream/_options/optionbool.py b/buildstream/_options/optionbool.py
index ffef55ca1..867de22df 100644
--- a/buildstream/_options/optionbool.py
+++ b/buildstream/_options/optionbool.py
@@ -43,9 +43,9 @@ class OptionBool(Option):
             self.value = _yaml.node_get(node, bool, self.name)
 
     def set_value(self, value):
-        if value == 'True' or value == 'true':
+        if value in ('True', 'true'):
             self.value = True
-        elif value == 'False' or value == 'false':
+        elif value in ('False', 'false'):
             self.value = False
         else:
             raise LoadError(LoadErrorReason.INVALID_DATA,
diff --git a/buildstream/_platform/darwin.py b/buildstream/_platform/darwin.py
index 04a83110e..292c0cb73 100644
--- a/buildstream/_platform/darwin.py
+++ b/buildstream/_platform/darwin.py
@@ -16,9 +16,7 @@
 #  License along with this library. If not, see <http://www.gnu.org/licenses/>.
 
 import os
-import resource
 
-from .._exceptions import PlatformError
 from ..sandbox import SandboxDummy
 
 from . import Platform
@@ -29,10 +27,6 @@ class Darwin(Platform):
     # This value comes from OPEN_MAX in syslimits.h
     OPEN_MAX = 10240
 
-    def __init__(self):
-
-        super().__init__()
-
     def create_sandbox(self, *args, **kwargs):
         kwargs['dummy_reason'] = \
             "OSXFUSE is not supported and there are no supported sandbox" + \
diff --git a/buildstream/_platform/linux.py b/buildstream/_platform/linux.py
index 09db19f2d..6e488472f 100644
--- a/buildstream/_platform/linux.py
+++ b/buildstream/_platform/linux.py
@@ -22,7 +22,6 @@ import subprocess
 
 from .. import _site
 from .. import utils
-from .._message import Message, MessageType
 from ..sandbox import SandboxDummy
 
 from . import Platform
@@ -112,8 +111,4 @@ class Linux(Platform):
         except subprocess.CalledProcessError:
             output = ''
 
-        if output == 'root':
-            return True
-
-        else:
-            return False
+        return output == 'root'
diff --git a/buildstream/_scheduler/jobs/job.py b/buildstream/_scheduler/jobs/job.py
index a1b90a080..60ae0d001 100644
--- a/buildstream/_scheduler/jobs/job.py
+++ b/buildstream/_scheduler/jobs/job.py
@@ -414,7 +414,7 @@ class Job():
 
             try:
                 # Try the task action
-                result = self.child_process()
+                result = self.child_process()  # pylint: disable=assignment-from-no-return
             except SkipJob as e:
                 elapsed = datetime.datetime.now() - starttime
                 self.message(MessageType.SKIPPED, str(e),
diff --git a/buildstream/_scheduler/queues/pullqueue.py b/buildstream/_scheduler/queues/pullqueue.py
index 2842c5e21..b861373a9 100644
--- a/buildstream/_scheduler/queues/pullqueue.py
+++ b/buildstream/_scheduler/queues/pullqueue.py
@@ -57,7 +57,7 @@ class PullQueue(Queue):
     def done(self, _, element, result, success):
 
         if not success:
-            return False
+            return
 
         element._pull_done()
 
diff --git a/buildstream/_scheduler/queues/trackqueue.py b/buildstream/_scheduler/queues/trackqueue.py
index 133655e14..514418086 100644
--- a/buildstream/_scheduler/queues/trackqueue.py
+++ b/buildstream/_scheduler/queues/trackqueue.py
@@ -20,7 +20,6 @@
 
 # BuildStream toplevel imports
 from ...plugin import _plugin_lookup
-from ... import SourceError
 
 # Local imports
 from . import Queue, QueueStatus
diff --git a/buildstream/_variables.py b/buildstream/_variables.py
index 1a52b5680..95b80cc08 100644
--- a/buildstream/_variables.py
+++ b/buildstream/_variables.py
@@ -191,8 +191,8 @@ def find_recursive_variable(variable, matched_variables, all_vars):
     for key, value in zip(matched_variables, matched_values):
         if _wrap_variable(variable) in value:
             return key
-    else:
-        return None
+    # We failed to find a recursive variable
+    return None
 
 
 def _wrap_variable(var):
diff --git a/buildstream/_workspaces.py b/buildstream/_workspaces.py
index adffaa694..468073f05 100644
--- a/buildstream/_workspaces.py
+++ b/buildstream/_workspaces.py
@@ -367,7 +367,7 @@ class Workspaces():
                 for element, config in _yaml.node_items(workspaces)
             }
 
-        elif version >= 1 and version <= BST_WORKSPACE_FORMAT_VERSION:
+        elif 1 <= version <= BST_WORKSPACE_FORMAT_VERSION:
             workspaces = _yaml.node_get(workspaces, dict, "workspaces", default_value={})
             res = {element: self._load_workspace(node)
                    for element, node in _yaml.node_items(workspaces)}
diff --git a/buildstream/_yaml.py b/buildstream/_yaml.py
index 30fc77291..90784636d 100644
--- a/buildstream/_yaml.py
+++ b/buildstream/_yaml.py
@@ -395,9 +395,9 @@ def node_get(node, expected_type, key, indices=None, default_value=_get_sentinel
         try:
             if (expected_type == bool and isinstance(value, str)):
                 # Dont coerce booleans to string, this makes "False" strings evaluate to True
-                if value == 'true' or value == 'True':
+                if value in ('True', 'true'):
                     value = True
-                elif value == 'false' or value == 'False':
+                elif value in ('False', 'false'):
                     value = False
                 else:
                     raise ValueError()
@@ -470,10 +470,11 @@ def node_get_project_path(node, key, project_dir, *,
                         .format(provenance, path_str))
 
     try:
+        full_path = (project_dir_path / path)
         if sys.version_info[0] == 3 and sys.version_info[1] < 6:
-            full_resolved_path = (project_dir_path / path).resolve()
+            full_resolved_path = full_path.resolve()
         else:
-            full_resolved_path = (project_dir_path / path).resolve(strict=True)
+            full_resolved_path = full_path.resolve(strict=True)  # pylint: disable=unexpected-keyword-arg
     except FileNotFoundError:
         raise LoadError(LoadErrorReason.MISSING_FILE,
                         "{}: Specified path '{}' does not exist"
diff --git a/buildstream/_yamlcache.py b/buildstream/_yamlcache.py
index 39b24cccc..6c3b4d639 100644
--- a/buildstream/_yamlcache.py
+++ b/buildstream/_yamlcache.py
@@ -27,9 +27,8 @@ import sys
 from contextlib import contextmanager
 from collections import namedtuple
 
-from ._cachekey import generate_key
 from ._context import Context
-from . import utils, _yaml
+from . import _yaml
 
 
 YAML_CACHE_FILENAME = "yaml_cache.pickle"
@@ -207,7 +206,7 @@ class YamlCache():
             filepath = os.path.relpath(full_path, project.directory)
         else:
             filepath = full_path
-        return full_path
+        return filepath
 
     # _calculate_key():
     #
@@ -329,7 +328,7 @@ class BstUnpickler(pickle.Unpickler):
                 if not project:
                     projects = [p.name for p in self._context.get_projects()]
                     raise pickle.UnpicklingError("No project with name {} found in {}"
-                                                 .format(key_id, projects))
+                                                 .format(project_tag, projects))
             else:
                 project = None
                 name = tagged_name
diff --git a/buildstream/buildelement.py b/buildstream/buildelement.py
index 3edc6d2a1..e57ca1c79 100644
--- a/buildstream/buildelement.py
+++ b/buildstream/buildelement.py
@@ -152,7 +152,7 @@ class BuildElement(Element):
     #############################################################
     def configure(self, node):
 
-        self.__commands = {}
+        self.__commands = {}  # pylint: disable=attribute-defined-outside-init
 
         # FIXME: Currently this forcefully validates configurations
         #        for all BuildElement subclasses so they are unable to
diff --git a/buildstream/element.py b/buildstream/element.py
index de1988d2a..6536d2582 100644
--- a/buildstream/element.py
+++ b/buildstream/element.py
@@ -432,7 +432,7 @@ class Element(Plugin):
                                                 visited=visited, recursed=True)
 
         # Yeild self only at the end, after anything needed has been traversed
-        if should_yield and (recurse or recursed) and (scope == Scope.ALL or scope == Scope.RUN):
+        if should_yield and (recurse or recursed) and (scope in (Scope.ALL, Scope.RUN)):
             yield self
 
     def search(self, scope, name):
@@ -1563,7 +1563,7 @@ class Element(Plugin):
                     # Step 3 - Prepare
                     self.__prepare(sandbox)
                     # Step 4 - Assemble
-                    collect = self.assemble(sandbox)
+                    collect = self.assemble(sandbox)  # pylint: disable=assignment-from-no-return
                     self.__set_build_result(success=True, description="succeeded")
                 except BstError as e:
                     # If an error occurred assembling an element in a sandbox,
@@ -2521,7 +2521,7 @@ class Element(Plugin):
         strong_key = meta['strong']
         weak_key = meta['weak']
 
-        assert key == strong_key or key == weak_key
+        assert key in (strong_key, weak_key)
 
         self.__metadata_keys[strong_key] = meta
         self.__metadata_keys[weak_key] = meta
diff --git a/buildstream/plugin.py b/buildstream/plugin.py
index 65b1b6e9d..9c5c0d8ca 100644
--- a/buildstream/plugin.py
+++ b/buildstream/plugin.py
@@ -751,9 +751,7 @@ class Plugin():
         self.__context.message(message)
 
     def __note_command(self, output, *popenargs, **kwargs):
-        workdir = os.getcwd()
-        if 'cwd' in kwargs:
-            workdir = kwargs['cwd']
+        workdir = kwargs.get('cwd', os.getcwd())
         command = " ".join(popenargs[0])
         output.write('Running host command {}: {}\n'.format(workdir, command))
         output.flush()
diff --git a/buildstream/plugins/sources/git.py b/buildstream/plugins/sources/git.py
index dbed87899..ced52d023 100644
--- a/buildstream/plugins/sources/git.py
+++ b/buildstream/plugins/sources/git.py
@@ -343,13 +343,13 @@ class GitMirror(SourceFetcher):
                                               '--contains', self.ref],
                                              cwd=fullpath,)
         if branch:
-            return True
+            return
         else:
             _, tag = self.source.check_output([self.source.host_git, 'tag', '--list', track,
                                                '--contains', self.ref],
                                               cwd=fullpath,)
             if tag:
-                return True
+                return
 
         detail = "The ref provided for the element does not exist locally in the provided track branch / tag " + \
                  "'{}'.\nYou may wish to track the element to update the ref from '{}' ".format(track, track) + \
diff --git a/buildstream/sandbox/_mount.py b/buildstream/sandbox/_mount.py
index 2dc3df2b5..aff9e8a2d 100644
--- a/buildstream/sandbox/_mount.py
+++ b/buildstream/sandbox/_mount.py
@@ -30,7 +30,7 @@ from .._fuse import SafeHardlinks
 # Helper data object representing a single mount point in the mount map
 #
 class Mount():
-    def __init__(self, sandbox, mount_point, safe_hardlinks, fuse_mount_options={}):
+    def __init__(self, sandbox, mount_point, safe_hardlinks, fuse_mount_options=None):
         scratch_directory = sandbox._get_scratch_directory()
         # Getting _get_underlying_directory() here is acceptable as
         # we're part of the sandbox code. This will fail if our
@@ -39,7 +39,7 @@ class Mount():
 
         self.mount_point = mount_point
         self.safe_hardlinks = safe_hardlinks
-        self._fuse_mount_options = fuse_mount_options
+        self._fuse_mount_options = {} if fuse_mount_options is None else fuse_mount_options
 
         # FIXME: When the criteria for mounting something and its parent
         #        mount is identical, then there is no need to mount an additional
@@ -101,10 +101,13 @@ class Mount():
 #
 class MountMap():
 
-    def __init__(self, sandbox, root_readonly, fuse_mount_options={}):
+    def __init__(self, sandbox, root_readonly, fuse_mount_options=None):
         # We will be doing the mounts in the order in which they were declared.
         self.mounts = OrderedDict()
 
+        if fuse_mount_options is None:
+            fuse_mount_options = {}
+
         # We want safe hardlinks on rootfs whenever root is not readonly
         self.mounts['/'] = Mount(sandbox, '/', not root_readonly, fuse_mount_options)
 
diff --git a/buildstream/sandbox/_mounter.py b/buildstream/sandbox/_mounter.py
index 921d06bb6..e6054c20d 100644
--- a/buildstream/sandbox/_mounter.py
+++ b/buildstream/sandbox/_mounter.py
@@ -25,7 +25,7 @@ from .. import utils, _signals
 
 
 # A class to wrap the `mount` and `umount` system commands
-class Mounter(object):
+class Mounter():
     @classmethod
     def _mount(cls, dest, src=None, mount_type=None,
                stdout=sys.stdout, stderr=sys.stderr, options=None,
diff --git a/buildstream/sandbox/_sandboxbwrap.py b/buildstream/sandbox/_sandboxbwrap.py
index 8c406e53e..fe429abe8 100644
--- a/buildstream/sandbox/_sandboxbwrap.py
+++ b/buildstream/sandbox/_sandboxbwrap.py
@@ -130,7 +130,7 @@ class SandboxBwrap(Sandbox):
         mount_source_overrides = self._get_mount_sources()
         for mark in marked_directories:
             mount_point = mark['directory']
-            if mount_point in mount_source_overrides:
+            if mount_point in mount_source_overrides:  # pylint: disable=consider-using-get
                 mount_source = mount_source_overrides[mount_point]
             else:
                 mount_source = mount_map.get_mount_source(mount_point)
diff --git a/buildstream/sandbox/_sandboxchroot.py b/buildstream/sandbox/_sandboxchroot.py
index f19052b23..aeba25137 100644
--- a/buildstream/sandbox/_sandboxchroot.py
+++ b/buildstream/sandbox/_sandboxchroot.py
@@ -72,7 +72,6 @@ class SandboxChroot(Sandbox):
         # each mount point needs to be mounted from and to
         self.mount_map = MountMap(self, flags & SandboxFlags.ROOT_READ_ONLY,
                                   self._FUSE_MOUNT_OPTIONS)
-        root_mount_source = self.mount_map.get_mount_source('/')
 
         # Create a sysroot and run the command inside it
         with ExitStack() as stack:
@@ -147,7 +146,7 @@ class SandboxChroot(Sandbox):
 
         try:
             with _signals.suspendable(suspend_proc, resume_proc), _signals.terminator(kill_proc):
-                process = subprocess.Popen(
+                process = subprocess.Popen(  # pylint: disable=subprocess-popen-preexec-fn
                     command,
                     close_fds=True,
                     cwd=os.path.join(rootfs, cwd.lstrip(os.sep)),
@@ -264,7 +263,7 @@ class SandboxChroot(Sandbox):
         @contextmanager
         def mount_point(point, **kwargs):
             mount_source_overrides = self._get_mount_sources()
-            if point in mount_source_overrides:
+            if point in mount_source_overrides:  # pylint: disable=consider-using-get
                 mount_source = mount_source_overrides[point]
             else:
                 mount_source = self.mount_map.get_mount_source(point)
diff --git a/buildstream/source.py b/buildstream/source.py
index e42bad1a5..483fd2341 100644
--- a/buildstream/source.py
+++ b/buildstream/source.py
@@ -637,7 +637,7 @@ class Source(Plugin):
             # Source consistency interrogations are silent.
             context = self._get_context()
             with context.silence():
-                self.__consistency = self.get_consistency()
+                self.__consistency = self.get_consistency()  # pylint: disable=assignment-from-no-return
 
     # Return cached consistency
     #
@@ -687,14 +687,14 @@ class Source(Plugin):
 
         key['directory'] = self.__directory
         if include_source:
-            key['unique'] = self.get_unique_key()
+            key['unique'] = self.get_unique_key()  # pylint: disable=assignment-from-no-return
 
         return key
 
     # Wrapper for set_ref(), also returns whether it changed.
     #
     def _set_ref(self, ref, node):
-        current_ref = self.get_ref()
+        current_ref = self.get_ref()  # pylint: disable=assignment-from-no-return
         changed = False
 
         # This comparison should work even for tuples and lists,
@@ -773,7 +773,7 @@ class Source(Plugin):
         elif project.ref_storage == ProjectRefStorage.PROJECT_REFS:
 
             # First warn if there is a ref already loaded, and reset it
-            redundant_ref = self.get_ref()
+            redundant_ref = self.get_ref()  # pylint: disable=assignment-from-no-return
             if redundant_ref is not None:
                 self.set_ref(None, {})
 
@@ -883,7 +883,7 @@ class Source(Plugin):
         else:
             new_ref = self.__do_track()
 
-        current_ref = self.get_ref()
+        current_ref = self.get_ref()  # pylint: disable=assignment-from-no-return
 
         if new_ref is None:
             # No tracking, keep current ref
@@ -1038,15 +1038,12 @@ class Source(Plugin):
         if not mirrors or not alias:
             return self.track(**kwargs)
 
-        context = self._get_context()
-        source_kind = type(self)
-
         # NOTE: We are assuming here that tracking only requires substituting the
         #       first alias used
         for uri in reversed(project.get_alias_uris(alias, first_pass=self.__first_pass)):
             new_source = self.__clone_for_uri(uri)
             try:
-                ref = new_source.track(**kwargs)
+                ref = new_source.track(**kwargs)  # pylint: disable=assignment-from-none
             # FIXME: Need to consider temporary vs. permanent failures,
             #        and how this works with retries.
             except BstError as e:
diff --git a/buildstream/utils.py b/buildstream/utils.py
index 7f2f9d5fd..0bddb287d 100644
--- a/buildstream/utils.py
+++ b/buildstream/utils.py
@@ -29,13 +29,13 @@ import re
 import shutil
 import signal
 import stat
+from stat import S_ISDIR
 import string
 import subprocess
 import tempfile
 import itertools
 import functools
 from contextlib import contextmanager
-from stat import S_ISDIR
 
 import psutil
 
@@ -1088,7 +1088,8 @@ def _call(*popenargs, terminate=False, **kwargs):
             os.killpg(group_id, signal.SIGCONT)
 
     with _signals.suspendable(suspend_proc, resume_proc), _signals.terminator(kill_proc):
-        process = subprocess.Popen(*popenargs, preexec_fn=preexec_fn, **kwargs)
+        process = subprocess.Popen(  # pylint: disable=subprocess-popen-preexec-fn
+            *popenargs, preexec_fn=preexec_fn, **kwargs)
         output, _ = process.communicate()
         exit_code = process.poll()