tree de43af900d722c45189dedcd2c30321686af5e77
parent e9becc079c647f6c9477eed83c0aecb2f591fdf4
author Dan Willemsen <dwillemsen@google.com> 1450215605 -0800
committer Dan Willemsen <dwillemsen@google.com> 1450218160 -0800

Fix prune when bare git has detached head

We don't really use HEAD much in the bare git repositories, but there
have been reports of errors in git-symbolic-ref:

  symbolic-ref: fatal: Refusing to point HEAD outside of refs/

That happen when the bare git repo is in the detached head state. It's
possible that previous operations were killed while we were pruning
branches.

Use DetachHead instead of SetHead if we're restoring the repo into a
detached head state.

Change-Id: I9062e8957bc70367d3ded399685ac026fbb421fc