fix an issue where private conversations were improperly merged when
merging user accounts (only a problem when it was being merged into an
existing conversation on the target user). this would cause page errors
due to orphaned conversation_participants.
includes a data migration to fix affected conversations.
test plan:
1. on the old code, create three users (A, B, C)
2. start a private conversation between A and B
3. start a private conversation between A and C
4. merge user B into user C
5. confirm that users A and C get a page error when going to conversations
6. upgrade the code and run the migration
7. confirm that conversations load and the merged conversation appears
correctly
8. on the new code, create three more users, repeat steps 2-4, and confirm
that conversations load and the merged conversation appears correctly
Change-Id: I50785764ae4376a38824ffa099ff678686ec5023
Reviewed-on: https://gerrit.instructure.com/9847
Tested-by: Hudson <hudson@instructure.com>
Reviewed-by: Cody Cutrer <cody@instructure.com>
Cody Cutrer