Merge branch 'lj/refs'

Merge branch 'lj/refs'

* lj/refs: (63 commits)
  Fix show-ref usagestring
  t3200: git-branch testsuite update
  sha1_name.c: avoid compilation warnings.
  Make git-branch a builtin
  ref-log: fix D/F conflict coming from deleted refs.
  git-revert with conflicts to behave as git-merge with conflicts
  core.logallrefupdates thinko-fix
  git-pack-refs --all
  core.logallrefupdates create new log file only for branch heads.
  Remove bashism from t3210-pack-refs.sh
  ref-log: allow ref@{count} syntax.
  pack-refs: call fflush before fsync.
  pack-refs: use lockfile as everybody else does.
  git-fetch: do not look into $GIT_DIR/refs to see if a tag exists.
  lock_ref_sha1_basic does not remove empty directories on BSD
  Do not create tag leading directories since git update-ref does it.
  Check that a tag exists using show-ref instead of looking for the ref file.
  Use git-update-ref to delete a tag instead of rm()ing the ref file.
  Fix refs.c;:repack_without_ref() clean-up path
  Clean up "git-branch.sh" and add remove recursive dir test cases.
  ...