Pull mirror failing

Summary

Repostiory mirroring has stopped working randomly Invalid reference name

Steps to reproduce

1. Create a pull mirror from github via gitlab
2. Create your webhook from github to gitlab
3. After X amount of time it seemed to have failed.

Example Project

https://gitlab.com/rawnet-deployment/hunters

What is the current bug behavior?

I can see in github that the webhook has recieved a 200 satus code, but gitlab says pull has failed with Invalid reference name

What is the expected correct behavior?

Its pulled the latest code updates.

Relevant logs and/or screenshots

Output of checks

This bug happens on GitLab.com