completion: query only refs/heads/ in __git_refs_remotes()

__git_refs_remotes() is used to provide completion for refspecs to set
'remote.*.fetch' config variables for branches on the given remote.
So it's really only interested in refs under 'refs/heads/', but it
queries the remote for all its refs and then filters out all refs
outside of 'refs/heads/'.

Let 'git ls-remote' do the filtering.

Also remove the unused $cmd variable from __git_refs_remotes().

Signed-off-by: SZEDER Gábor <szeder@ira.uka.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

contrib/completion/git-completion.bash

@@ -651,17 +651,14 @@ __git_refs2 ()
 # __git_refs_remotes requires 1 argument (to pass to ls-remote)
 __git_refs_remotes ()
 {
-	local cmd i is_hash=y
-	for i in $(git ls-remote "$1" 2>/dev/null); do
-		case "$is_hash,$i" in
-		n,refs/heads/*)
+	local i is_hash=y
+	for i in $(git ls-remote "$1" 'refs/heads/*' 2>/dev/null); do
+		case "$is_hash" in
+		n)
 			is_hash=y
 			echo "$i:refs/remotes/$1/${i#refs/heads/}"
 			;;
-		y,*) is_hash=n ;;
-		n,*^{}) is_hash=y ;;
-		n,refs/tags/*) is_hash=y;;
-		n,*) is_hash=y; ;;
+		y) is_hash=n ;;
 		esac
 	done
 }