Fix deployment when no YAML files are deleted

Resolves bug introduced in commit 9c61e2f0.

.gitlab-ci.yml

@@ -30,7 +30,7 @@ generate:
     # that USER and PASSWORD contain credentials of a user which has
     # permission to push to the neighbouring project.
     - cd CI
-    - git ls-files --deleted | xargs git rm
+    - git ls-files --deleted | xargs -r git rm
     - git add *.yml
     - git diff --cached --quiet --exit-code || git commit -m "Refresh YAML files" -m "Generated by $CI_PIPELINE_URL"
     - URL=${CI_REPOSITORY_URL#*@}