Code review comment for lp://staging/~brz/loggerhead/breezy

Sorry for the long delay here; it took me a long time to get a suitable Breezy-using Launchpad branch set up so that I could test the integration.

As well as the minor comments here, https://code.launchpad.net/~cjwatson/loggerhead/more-no-file-ids/+merge/372951 is needed.