Summary:
Ref T9028. This allows us to detect when commits are unreachable:
- When a ref (tag, branch, etc) is moved or deleted, store the old thing it pointed at in a list.
- After discovery, go through the list and check if all the stuff on it is still reachable.
- If something isn't, try to follow its ancestors back until we find something that is reachable.
- Then, mark everything we found as unreachable.
- Finally, rebuild the repository summary table to correct the commit count.
Test Plan:
- Deleted a ref, ran `pull` + `refs`, saw oldref in database.
- Ran `discover`, saw it process the oldref, mark the unreachable commit, and update the summary table.
- Visited commit page, saw it properly marked.
Reviewers: chad
Reviewed By: chad
Maniphest Tasks: T9028
Differential Revision: https://secure.phabricator.com/D16133
