Correct some issues around IMPORTED_PERMANENT in RefEngine
Summary: Ref T13591. Fixes a few issues with the recent updates here discovered in more thorough testing.
Test Plan:
- Stopped the daemons.
- Created a new copy of Phabricator in Diffusion.
- Pulled it with `bin/repository pull ...`.
- Got 17,278 commits on disk with `git log --all --format=%H`.
- Set permanent refs to "master".
- Discovered it with `bin/repository discover ...`.
- This took 31.5s and inserted 17,278 tasks.
- Verified that all tasks have priority 4,000 (PRIORITY_IMPORT).
- Observed that 16,799 commits have IMPORTED_PERMANENT and 479 commits do not.
- This matches `git log master --format=%H` exactly.
- Ran `bin/repository refs ...`. Expected no changes and saw no changes.
- Ran `bin/worker execute --active` for a minute or two. It processed all the impermanent changes first (since `bin/worker` is LIFO and these are supposed to process last).
- Ran `bin/repository refs`. Expected no changes and saw no changes.
- Marked all refs as permanent.
- Starting state: 16,009 message tasks, all at priority 4000.
- Ran `bin/repository refs`, expecting 479 new tasks at priority 4000.
- Saw count rise to 16,488 as expected.
- Saw all the new tasks have priority 4000 and all commits now have the IMPORTED_PERMANENT flag.
Maniphest Tasks: T13591
Differential Revision: https://secure.phabricator.com/D21518