completion: improve ls-remote output filtering in __git_refs_remotes()

This follows suit of a previous patch for __git_refs(): use a
while-read loop and let bash's word splitting get rid of object names
from 'git ls-remote's output.

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

contrib/completion/git-completion.bash

@@ -651,15 +651,10 @@ __git_refs2 ()
 # __git_refs_remotes requires 1 argument (to pass to ls-remote)
 __git_refs_remotes ()
 {
-	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 ;;
-		esac
+	local i hash
+	git ls-remote "$1" 'refs/heads/*' 2>/dev/null | \
+	while read hash i; do
+		echo "$i:refs/remotes/$1/${i#refs/heads/}"
 	done
 }