Fix "morph edit" to load morphologies from git when needed

This is a bug fix. The code would previously blithely load the
morphology from the currently checked out ref (plus any local,
uncommitted changes). This is obviously wrong. However, we can't
check out the right ref, either, so the right thing to do is to
"git cat-file" it. But only when the right ref is not checked out.

This is fairly complex behaviour which may not be obvious to users
either. But we'll worry about that later, this is what needs to
happen now, and I don't want to make big behavioural changes in
the middle of a refactoring.

Bug found based on suggestion by Richard Maw.

1 files changed, 32 insertions, 1 deletions

diff --git a/morphlib/plugins/branch_and_merge_new_plugin.py b/morphlib/plugins/branch_and_merge_new_plugin.py
index 82fab13d..ac28c5f0 100644
--- a/morphlib/plugins/branch_and_merge_new_plugin.py
+++ b/morphlib/plugins/branch_and_merge_new_plugin.py
@@ -256,6 +256,17 @@ class SimpleBranchAndMergePlugin(cliapp.Plugin):
         gd.update_submodules(self.app)
         gd.update_remotes()
 
+    def _load_morphology_from_file(self, loader, dirname, filename):
+        full_filename = os.path.join(dirname, filename)
+        return loader.load_from_file(full_filename)
+
+    def _load_morphology_from_git(self, loader, gd, ref, filename):
+        try:
+            text = gd.cat_file('blob', ref, filename)
+        except cliapp.AppException:
+            text = gd.cat_file('blob', 'origin/%s' % ref, filename)
+        return loader.load_from_string(text, filename)
+
     def _load_stratum_morphologies(self, loader, sb, system_morph):
         logging.debug('Starting to load strata for %s' % system_morph.filename)
         lrc, rrc = morphlib.util.new_repo_caches(self.app)
@@ -266,14 +277,34 @@ class SimpleBranchAndMergePlugin(cliapp.Plugin):
             if not morphset.has(repo_url, ref, filename):
                 logging.debug('Loading: %s %s %s' % (repo_url, ref, filename))
                 dirname = sb.get_git_directory_name(repo_url)
+
+                # Get the right morphology. The right ref might not be
+                # checked out, in which case we get the file from git.
+                # However, if it is checked out, we get it from the
+                # filesystem directly, in case the user has made any
+                # changes to it. If the entire repo hasn't been checked
+                # out yet, do that first.
+
                 if not os.path.exists(dirname):
                     self._checkout(lrc, sb, repo_url, ref)
-                m = loader.load_from_file(sb.get_filename(repo_url, filename))
+                    m = self._load_morphology_from_file(
+                        loader, dirname, filename)
+                else:
+                    gd = morphlib.gitdir.GitDirectory(dirname)
+                    if gd.is_currently_checked_out(ref):
+                        m = self._load_morphology_from_file(
+                            loader, dirname, filename)
+                    else:
+                        m = self._load_morphology_from_git(
+                            loader, gd, ref, filename)
+
                 m.repo_url = repo_url
                 m.ref = ref
                 m.filename = filename
+
                 morphset.add_morphology(m)
                 queue.extend(self._get_stratum_triplets(m))
+
         logging.debug('All strata loaded')
         return morphset