Merge branch 'master' into jc/fsck-reflog

* master:
  Introduce a global level warn() function.
  Rename imap-send's internal info/warn functions.
  _XOPEN_SOURCE problem also exists on FreeBSD
  parse-remote: mark all refs not for merge only when fetching more than one
  git-reset --hard: tell the user what the HEAD was reset to
  git-tag: support -F <file> option
  Revert "git-pull: refuse default merge without branch.*.merge"
  Suggest 'add' in am/revert/cherry-pick.
  Use git-merge-file in git-merge-one-file, too
  diff --check: fix off by one error
  Documentation/git-branch: new -r to delete remote-tracking branches.
  Fix system header problems on Mac OS X
  spurious .sp in manpages