R1:e26c4bddab33

Replace magical "branch" behavior in "diffusion.branchquery" with an explicit "patterns"

Summary:
See PHI958. Ref T13210. Previously, see PHI720.

The use case for the magic in PHI720 involves multiple patterns, and no parameter can be passed to `branch` that will result in multiple patterns being passed to `git`.

Replace the implicit magic with an explicit `patterns` parameter.

This whole thing is a bit shaky but probably isn't hurting anything.

Test Plan:
- Ran query with no `patterns`.
- Ran…