After updating to use the v4 graphql api in the merge tooling, the githubTargetBranch
was set to be the sha of the latest commit rather than the branch name of the target
branch. This caused our tooling to mismatch which branches were actually being targeted
with the effect that if a PR targeted only the patch branch (i.e. labeled `target: patch`
and targeting `11.2.x` in github)it would still expect to merge into both `11.2.x` and
`master`. This is now corrected to once again use the branch name, restoring to the
previous functionality.
PR Close#41523