completion: teach replace to complete options

Git-replace needs to complete references and its own options. In
addition to the existing references completions, do also complete the
options --edit --graft --format= --list --delete.

Signed-off-by: Cornelius Weig <cornelius.weig@tngtech.com>
Reviewed-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: Cornelius Weig

contrib/completion/git-completion.bash

@@ -2408,6 +2408,12 @@ _git_remote ()
 
 _git_replace ()
 {
+	case "$cur" in
+	--*)
+		__gitcomp "--edit --graft --format= --list --delete"
+		return
+		;;
+	esac
 	__gitcomp_nl "$(__git_refs)"
 }