There are a couple of flaky tests, encryption_drop_partition,q and encryption_drop_table.q, that sometimes fail on jenkins because a previous q-test, encryption_with_trash.q, is disabling the trash.
Trash is set automatically in QTestUtil.java. I don't remember why it was due that way, probably because some issues with other tests.
The best way to fix this is to delete encryption_with_trash.q. This test is not necessary and redundant, so it is safe to delete it.