b&m: Add new-status subcommand

This currently performs the workspace-wide status, but not the
system-branch status functionality of the older status subcommand.

A quick estimate showed the new code to be 5x faster, comparing

    # time (echo 2 >/proc/sys/vm/drop_caches; morph status)
    System branches in current workspace:
        baserock/richardmaw/S8537/ssh-copy-id
        baserock/richardmaw/S8564/ro-staging-area
        baserock/richardmaw/S8591/lzo-shared
        baserock/richardmaw/cliapp-pipefail
        baserock/richardmaw/malformed-strata-test
        master
        tutorial-1/tutorial/master
        tutorial-1/tutorial/update-ssh

    real	0m2.517s
    user	0m0.998s
    sys	0m1.482s
    # time (echo 2 >/proc/sys/vm/drop_caches; morph new-status)
    System branches in current workspace:
        baserock/richardmaw/S8537/ssh-copy-id
        baserock/richardmaw/S8564/ro-staging-area
        baserock/richardmaw/S8591/lzo-shared
        baserock/richardmaw/cliapp-pipefail
        baserock/richardmaw/malformed-strata-test
        master
        tutorial-1/tutorial/master
        tutorial-1/tutorial/update-ssh

    real	0m0.506s
    user	0m0.207s
    sys	0m0.233s

1 files changed, 48 insertions, 0 deletions

diff --git a/morphlib/plugins/branch_and_merge_new_plugin.py b/morphlib/plugins/branch_and_merge_new_plugin.py
index 66231de9..bf24baba 100644
--- a/morphlib/plugins/branch_and_merge_new_plugin.py
+++ b/morphlib/plugins/branch_and_merge_new_plugin.py
@@ -53,6 +53,8 @@ class SimpleBranchAndMergePlugin(cliapp.Plugin):
             'show-branch-root', self.show_branch_root, arg_synopsis='')
         self.app.add_subcommand('foreach', self.foreach,
                                 arg_synopsis='-- COMMAND [ARGS...]')
+        self.app.add_subcommand('new-status', self.status,
+                                arg_synopsis='')
 
     def disable(self):
         pass
@@ -741,3 +743,49 @@ class SimpleBranchAndMergePlugin(cliapp.Plugin):
 
         # Write morphologies back out again.
         self._save_dirty_morphologies(loader, sb, morphs.morphologies)
+
+    def status(self, args):
+        '''Show information about the current system branch or workspace
+
+        This shows the status of every local git repository of the
+        current system branch. This is similar to running `git status`
+        in each repository separately.
+
+        If run in a Morph workspace, but not in a system branch checkout,
+        it lists all checked out system branches in the workspace.
+
+        '''
+
+        if args:
+            raise cliapp.AppException('morph status takes no arguments')
+
+        ws = morphlib.workspace.open('.')
+        try:
+            sb = morphlib.sysbranchdir.open_from_within('.')
+        except morphlib.sysbranchdir.NotInSystemBranch:
+            self._workspace_status(ws)
+        else:
+            self._branch_status(ws, sb)
+
+    def _workspace_status(self, ws):
+        '''Show information about the current workspace
+
+        This lists all checked out system branches in the workspace.
+
+        '''
+        self.app.output.write("System branches in current workspace:\n")
+        branches = sorted(ws.list_system_branches(),
+                          key=lambda x: x.root_directory)
+        for sb in branches:
+            self.app.output.write("    %s\n" % sb.get_config('branch.name'))
+
+    def _branch_status(self, ws, sb):
+        '''Show information about the current branch
+
+        This shows the status of every local git repository of the
+        current system branch. This is similar to running `git status`
+        in each repository separately.
+
+        '''
+        pass
+