Merge branch 'sg/complete-refs'

* sg/complete-refs:
  completion: remove broken dead code from __git_heads() and __git_tags()
  completion: fast initial completion for config 'remote.*.fetch' value
  completion: improve ls-remote output filtering in __git_refs_remotes()
  completion: query only refs/heads/ in __git_refs_remotes()
  completion: support full refs from remote repositories
  completion: improve ls-remote output filtering in __git_refs()
  completion: make refs completion consistent for local and remote repos
  completion: optimize refs completion
  completion: document __gitcomp()

Conflicts:
	contrib/completion/git-completion.bash

Author: gitster