fetch the source branch for generating the shortlog

.github/workflows/openshift-os.yml

@@ -74,9 +74,11 @@ jobs:
           git submodule update
 
           cd fedora-coreos-config
+          # the submodule init only fetch the submodule commit and the default branch `testing-devel`
+          git fetch origin ${SOURCE_BRANCH}
           # Omit CoreOS Bot commits from the log message, since they generally
           # only affect FCOS
-          git shortlog "HEAD..$SOURCE_BRANCH" --perl-regexp \
+          git shortlog "HEAD..FETCH_HEAD" --perl-regexp \
               --author='^((?!CoreOS Bot <[email protected]>).*)$' \
               > $RUNNER_TEMP/shortlog