use the right revision
diff --git a/tools/build_uec.sh b/tools/build_uec.sh
index 98b39b9..2a69952 100755
--- a/tools/build_uec.sh
+++ b/tools/build_uec.sh
@@ -175,7 +175,7 @@
 cd devstack
 git remote set-url origin `cd $TOP_DIR; git remote show origin | grep Fetch | awk '{print $3}'`
 git fetch
-git checkout $GIT_COMMIT
+git checkout `git rev-parse HEAD`
 cat > localrc <<LOCAL_EOF
 `cat $TOP_DIR/localrc`
 LOCAL_EOF