deleted or merged persons/teams can have memberships left over which cannot be revoked

[Daniel Holbach]

Symptoms
========

Delete user foo (or team foo). Someone else adds foo to a team at the same time. After the delete the user or team will still be in the new team (sometimes).

A 403 will be raised if the merged team was private. Even if the team was deactivated,
the +members page can not be viewed by team admins because no one has permission to
view the merged team.

Diagnosis
=========

When person foo is deleted / merged a job executes to remove all the teams / memberships. This is naturally racey - unless it is delayed longer than the longest possible web transaction, it will not see all newly added memberships, and there are nothing causing contention on common rows, so neither transaction will fail.

The current situation is that we run the update job after most transactions so new occurrences of this should be fairly rare (but short of an audit, not impossible).

Possible solutions
==================

* Run a garbo job looking for memberships of deleted person/teams.

* Ensure that the purge process runs after *all* possible transactions adding membership (and team participation) rows... web ops, scripts, backend jobs.

A garbo job will have progressively slower performance but is simple to implement.

[Daniel Holbach (dholbach)]

This currently breaks a script I need to get the loco-directory rolling. :-)

[Curtis Hovey (sinzui)]

I think we want a garbo job to clean this up daily.

[Robert Collins (lifeless)]

There are race conditions here; adding FOO to team BAR does not alter the FOO row itself, so no conflict is generated. So yes, a garbo job is indeed needed.

[Curtis Hovey (sinzui)]

There is a secondary case where the team merged team is already deactivated and it continues to be listed, but a 403 error will be raised because both the object and the page cannot be accessed even by Lp admins.

[Launchpad QA Bot (lpqabot)]

Fixed in stable r16338 <http://bazaar.launchpad.net/~launchpad-pqm/launchpad/stable/revision/16338>.