[packages/rpm-build-tools] Fix for initialized git repo without any config

[draenog]

commit acd0d41d0d2244293a5c1bbd7f9624d3dc998581
Author: Kacper Kornet <draenog at pld-linux.org>
Date:   Wed Aug 8 18:34:58 2012 +0100

    Fix for initialized git repo without any config
    
    Previous version failed in the repo initialized by git init but before
    the first commit was committed to it. The reason was that
    git symbolic-ref HEAD returns refs/heads/master, however
    git checkout-master failed. The solution is to check if HEAD points to a
    real commit with git-rev-parse.

 builder.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/builder.sh b/builder.sh
index 35b070e..edd84a1 100755
--- a/builder.sh
+++ b/builder.sh
@@ -796,7 +796,7 @@ init_builder() {
 	export GIT_WORK_TREE=$PACKAGE_DIR
 	export GIT_DIR=$PACKAGE_DIR/.git
 
-	if [ -d "$GIT_DIR" ] && [ -z "$CVSTAG" ]; then
+	if [ -d "$GIT_DIR" ] &&  [ -z "$CVSTAG" ] && git rev-parse --verify -q HEAD > /dev/null; then
 		if CVSTAG=$(GIT_DIR=$GIT_DIR git symbolic-ref HEAD) 2>/dev/null; then
 			CVSTAG=${CVSTAG#refs/heads/}
 			if [ "$CVSTAG" != "master" ]; then