If a user is pushing directly to refs/meta/config new commits are
supposed to be validated for correct author and committer lines.
Previously the server was checking all commits on the history of
refs/meta/config due to a bug in the markHeadsAsUninteresting method
skipping references outside of refs/heads.
Instead always include the current value of the reference being
updated in the uninteresting set.
Bug: issue 1842
Change-Id: Ic834bc87cdaa7bfdf8b1e97d4f02b6a9bfb8cb0a
dd232477ef