Make sure not to revert local changes.

"git diff --quiet" has a bug ignoring local changes if there's a
unchanged file with a newer timestamp.  This patch works around
the bug.

Change-Id: I0ddc24e0f7af21287c43c1e04dd166ebff6f2dca
Closes-Bug: 1264422
diff --git a/functions b/functions
index 92b61ed..eb92a6c 100644
--- a/functions
+++ b/functions
@@ -1301,7 +1301,8 @@
     echo "cd $REQUIREMENTS_DIR; $SUDO_CMD python update.py $project_dir"
 
     # Don't update repo if local changes exist
-    (cd $project_dir && git diff --quiet)
+    # Don't use buggy "git diff --quiet"
+    (cd $project_dir && git diff --exit-code >/dev/null)
     local update_requirements=$?
 
     if [ $update_requirements -eq 0 ]; then