Add debug message in RepositoryManager.notify when ChangesetNotFound

[ethan.jucovy@…]

If RepositoryManager.notify is called with an invalid changeset, the core system catches the NoSuchChangeset error and silently ignores the error, skipping all subscribed change_listeners without calling their methods.

(The situation can easily be reproduced by calling trac-admin $ENV changeset added $REPO gibberish on the command line.)

There is currently no trace of this in logging output, which can cause user confusion, and makes it unclear where the problem is. A user might not immediately realize that the provided changeset was invalid, and could assume that the problem is a bug in Trac itself and/or a plugin.

Adding some debug output would address the potential user confusion:

trac/versioncontrol/api.py

@@ -694 +694 @@
                     try:
                         repos.sync_changeset(rev)
                         changeset = repos.get_changeset(rev)
-                    except NoSuchChangeset:
+                    except NoSuchChangeset, e:
+                        self.log.debug("No changeset %s found in repository %s; skipping subscribers for event %s" % (rev, repos.reponame, event))
                         continue
                 self.log.debug("Event %s on %s for revision %s",
                                event, repos.reponame or '(default)', rev)

See ​trac-users thread for more details.