Hidden characters causing .gitlab-ci.yml to fail -

Unsure if to categorize this as a bug, or just a bad byproduct of "oops"

We spent the last week debugging why an "only" stage on a feature branch was failing. We recently migrated to GitLab and have been working off feature branches. We added the CI config to master, and then copied it to the feature branches.

We had a weird experience that master ran fine, but kept failing in feature. Feature kept saying there were no jobs visible. "Jobs config should contain at least one visible job"

Turns out, in the start of the file, somehow the characters \357\273\277 were in the CI Yaml file.

Deleted the file, recreated it with a safe version of CI YAML and voila - working.

So, while not necessarily a bug (couldn't parse input) - perhaps a better error message is due? Hopefully this helps someone else.