merge causes OOPs in Person:+participation by introducing missing key in getPathsToTeams()

I believe this issue relates to bug 651210 [Spurious entries in TeamParticipation]. I suspect this is an exacerbation of an older issue with merge.

The getPathsToTeams() method gets all the TP entries for the IPerson, filter out self, then builds a graph of all the TeamMemberships for the TP.team ids. *But* the graph cannot be built because the TP key is not in the TM data.

In the last few days, ~canonical-mobile, ~ubuntu-cl-website, and ~ubuntu-cl-dev teams were deleted. I believe merge is broken because ~registry should not be members of super teams that the deleted teams belonged to (/me struggles to keep ~registry's memberships sane). Delete uses revokeTeamMembership() for all direct team memberships before doing completing the merge.

The expectation is that all TP entries are correct before the merge process starts. The _mergeTeamMembership() step does work with both TM and TP, but maybe it fails because the data changes are not flushed to the db. TP has triggers; maybe the db is not in the state we think.

We see a number of problems in the execution chain that needs fixing.

* AdminTeamMergeView.deactivate_members_and_merge_action
  removes the team members, call flush_database_updates, then
  call doMerge that removes the super teams. flush_database_updates is
  not called.
  ! This is why the super teams were transferred to ~registry later
    in Person._mergeTeamMemberships().
  ! Moved the remove members and flush call to the do merge method so
    all the setup operations happen in the expected order.

* Person._mergeTeamMemberships() was never intended for teams; the view
  aborted merge. There is already a guard to ensure a team with members is
  not passed.
  ! Add an assert in the merge() method to ensure it fails if the team has
    super teams.

* Person.deactivateAllMembers() used a single db calls to remove the members,
  but only the direct entries in TeamParticipation are deleted. The indirect
  entries are not removed. This issue overlaps with bug 651210
  ! This is why getPathsToTeams() in +participation fails.
  ! The Person.teams_participated_in can be adapted to provide a complete set
    of entries that must be removed for all team members.

Fixed in stable r12016 <http://bazaar.launchpad.net/~launchpad-pqm/launchpad/stable/revision/12016>.

The branch landed seems to address issues related to this, but qa shows there's still something going wrong. Tagging it as incremental and in progress; there's a chance this has something to do with triggers on TP, not the code addressed in the branch.

Switched to qa-ok from 'incr'; mixing up my landing directives with bug tags. Bug is still in progress.

Fixed in stable r12047 <http://bazaar.launchpad.net/~launchpad-pqm/launchpad/stable/revision/12047>.