Merge branch 'nd/complete-format-patch'

The support for format-patch (and send-email) by the command-line
completion script (in contrib/) has been simplified a bit.

* nd/complete-format-patch:
  completion: use __gitcomp_builtin for format-patch

diff --cc contrib/completion/git-completion.bash
Simple merge

diff --cc git-send-email.perl
Simple merge