Merge branch 'ls/complete-remote-update-names'

"git remote update" can take both a single remote nickname and a
nickname for remote groups, and the completion script (in contrib/)
has been taught about it.

* ls/complete-remote-update-names:
  completion: complete remote names too

Author: gitster

contrib/completion/git-completion.bash

@@ -2362,7 +2362,7 @@ _git_remote ()
 		__gitcomp_builtin remote_update
 		;;
 	update,*)
-		__gitcomp "$(__git_get_config_variables "remotes")"
+		__gitcomp "$(__git_remotes) $(__git_get_config_variables "remotes")"
 		;;
 	set-url,--*)
 		__gitcomp_builtin remote_set-url