sometimes diff shown in git merge proposal is not updated

[Scott Moser]

Sometimes launchpad's diff shown in a merge proposal does not get updated
when branch does. We see this from time to time, but do not understand the
circumstances under which it appears.

One example of it can be seen (currently) at
  https://code.launchpad.net/~smoser/cloud-init/+git/cloud-init/+merge/324401

Note that the 'Preview Diff' only has an old commit hash (d6518ba into 3d97b29)
in it, which does not match the 'Unmerged commits' entry (9c33cb22)

If you follow the link to the commit you'll see the correct diff. The 'systemd'
related changes should not be present.

As other information that might be helpful:
 * I pushed to this branch submitted for review, and then quickly pushed again
   dropping a commit.
 * Chad might have reviewed in between those two pushes.

[Joshua Powers (powersj)]

Here are some of the OOPS IDs that I have had when I run across this:

OOPS-0b0b753bb13cdd64ed575dfcf006580a
OOPS-4804f7168fd5bcf61839c997789112c4
OOPS-1abf4831a15e20d0f34b08c4e0390cda
OOPS-e452bec09711d44ff1a102538807d0e2

[Colin Watson (cjwatson)]

Already fixed in r18387 (http://bazaar.launchpad.net/~launchpad-pqm/launchpad/stable/revision/18387), which I'll roll out shortly.

[Colin Watson (cjwatson)]

That's rolled out now. If the diffs don't catch up by themselves, then you can use the git_repository.rescan API method (https://launchpad.net/+apidoc/devel.html#git_repository-rescan).

[Colin Watson (cjwatson)]

(Though in general Merged MPs tend to be left alone.)