Prevent "Maniphest Tasks" field from creating empty comment when revisions are updated
Summary:
- If you update a revision with a nonempty "Maniphest Tasks" field, an empty
comment is posted (see T586).
- The transaction email currently says "Attached revision 'Unknown
Differential Revision'", move attaching to "didWriteRevision()" to make sure the
object has been written.
Test Plan: - Attached; updated a revision.
Reviewers: btrahan, jungejason
Reviewed By: btrahan
CC: aran, btrahan
Maniphest Tasks: T685
Differential Revision: 1223