test_rfc5490_mailboxexists_variables fails for 3.0

[elliefm]

This looks like an actual Cyrus bug. The test sends two messages and expects one to land in the hit folder, the other in the miss folder.

On 3.0, they both wind up in the same folder (not sure which, I haven't looked into this deeply yet), causing the test to fail with either "expected 1, got 0" or "expected 1, got 2" (depending on which folder it checks first, I'm not sure if the order is significant).

It's fine on master.

@ksmurchison Are you aware of anything that'd cause this in the older implementation? I don't want to backport your recent refactor, but maybe it was already fixed before that? Or maybe this was the issue that prompted the refactor? I'm not sure!

[elliefm]

cyrusimap/cassandane#54 is the same issue on the Cassandane repository fwiw.

[elliefm]

This was fixed in 3387587 on master, and Ken has cherry-picked it to 3.0 as bb1716d