Modernize Diffusion commitparentsquery
Summary: Ref T4195. Ref T2783. We have an old-school implementation of this; move it into a LowLevel query and make callers all run through Conduit. I need the LowLevel query for hooks, to implement an "is merge commit" Herald rule.
Test Plan:
- Ran query via Conduit for SVN, Mercurial, Git.
- Parsed a commit which closed a revision, attach/closed worked correctly.
- Browsed Diffusion.
Reviewers: btrahan
Reviewed By: btrahan
CC: aran
Maniphest Tasks: T4195, T2783
Differential Revision: https://secure.phabricator.com/D7808