Revision not present errors due to push creating stacked 2a repositories with format 6 (unstacked) branches

[Tim Penhey]

Branches are sometimes created with format 6 even though the initial push code thought it would be stacked and seeded it like a stacked branch.

Workarounds
===========

Before pushing make sure branches are in branch 7 format (run 'bzr upgrade --2a' on them)

After pushing, if a branch is affected

bzr upgrade --2a sftp://bazaar.launchpad.net/USER/PROJECT/BRANCH
python
import bzrlib.branch
b = bzrlib.branch.Branch.open('sftp://bazaar.launchpad.net/USER/PROJECT/BRANCH')
b.set_stacked_on_url('sftp://bazaar.launchpad.net/<trunk for project>')

Causes
======

Still being analyzed

Details
======

Somehow several different users with format 2a repositories are pushing broken branches to Launchpad. Specifically they have created stacked repositories, but format 6 branches, so when accessing history outside of the stacked repository the user (and Launchpad internals like the scanner) get RevisionNotPresent errors. This may be caused by #390431.

Example branches affected by this:

lp:~danilo/launchpad/bug-389391
lp:~julian-edwards/launchpad/team-join-sub-email-bug-382687
lp:~jml/launchpad/fix-run-all

[Andrew Bennetts (spiv)]

The traceback shows it is failing in iter_reverse_revision_history, on a revision from PQM. I assume these are stacked branches. Perhaps the stacked-on branch isn't branch/repository isn't working properly?

Hmm:

$ bzr revision-history lp:~jml/launchpad/fix-run-all
bzr: ERROR: Server sent an unexpected error: ('error', 'Revision {<email address hidden>} not present in "CHKInventoryRepository(\'lp-140472760815824:///~jml/launchpad/fix-run-all/.bzr/repository\')".')

Same via SFTP.

Oh, interesting... "bzr info -v" on that branch shows:

        branch: Branch format 6

So, I think this is a recurrence of a bug we used to have where a stacked repository gets pushed up, then a format 6 (and thus unstacked) branch gets created on that repository.

[Andrew Bennetts (spiv)]

Possibly the same as bug #390431. See <https://bugs.edge.launchpad.net/bzr/+bug/390431/comments/1>

[Jonathan Lange (jml)]

See OOPS-1283SMS1, OOPS-1283SMS10, OOPS-1283SMS100, OOPS-1283SMS1000, OOPS-1283SMS1003, OOPS-1283SMS1001, OOPS-1283SMS1004, OOPS-1283SMS1007, OOPS-1283SMS101, OOPS-1283SMS1010, OOPS-1283SMS1002, OOPS-1283SMS1005, OOPS-1283SMS1008, OOPS-1283SMS1011 and OOPS-1283SMS1014 for examples.