Cast branch to string or otherwise it fails

module_build_service/utils.py

@@ -364,7 +364,7 @@ def _fetch_mmd(url, branch = None, allow_local_url = False):
                               'does not match the branch "{1}"'.format(
                                   mmd.stream, scm.branch))
     else:
-        mmd.stream = scm.branch
+        mmd.stream = str(scm.branch)
 
     # If the version is in the modulemd, throw an exception since the version
     # is generated by pdc-updater