Merge branch 'jl/complete-git-prune' into next

Add "git prune" to the completion (in contrib/), which could be
typed by end-users from the command line.

* jl/complete-git-prune:
  bash-completion: add git-prune into bash completion

Author: gitster

command-list.txt

@@ -136,7 +136,7 @@ git-pack-redundant                      plumbinginterrogators
 git-pack-refs                           ancillarymanipulators
 git-parse-remote                        synchelpers
 git-patch-id                            purehelpers
-git-prune                               ancillarymanipulators
+git-prune                               ancillarymanipulators   complete
 git-prune-packed                        plumbingmanipulators
 git-pull                                mainporcelain           remote
 git-push                                mainporcelain           remote