Merge branch 'dl/complete-stash'

The command line completion (in contrib/) for "git stash" has been
updated.

* dl/complete-stash:
  git-completion.bash: use __gitcomp_builtin() in _git_stash()
  git-completion.bash: extract from else in _git_stash()
  git-completion.bash: pass $__git_subcommand_idx from __git_main()

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