[packages/rpm-build-tools] Use git-show-ref -s to get SHA1 of tag

[draenog]

commit 7baf7b2fc6db466d01023cb6eb569c71ae4f85cd
Author: Kacper Kornet <draenog at pld-linux.org>
Date:   Sun Jul 15 21:17:06 2012 +0100

    Use git-show-ref -s to get SHA1 of tag

 builder.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/builder.sh b/builder.sh
index 4312680..1c096b8 100755
--- a/builder.sh
+++ b/builder.sh
@@ -1331,7 +1331,7 @@ tag_exist() {
 	if [ -n "$DEPTH" ]; then
 		local ref=$(git ls-remote $REMOTE_PLD "refs/tags/$_tag"  | cut -c -40)
 	else
-		local ref=$(git show-ref "refs/tags/$_tag" | cut -c -40)
+		local ref=$(git show-ref -s "refs/tags/$_tag")
 	fi
 	[ -z "$ref" ] && return 0
 	[ "$ref" = "$sha1" ] || Exit_error err_tag_exists "$_tag"