Pull mirroring from GitHub does not pull squashed commits

Summary

Pull mirroring from GitHub does not pull squashed commits

Steps to reproduce

• in GitLab, configure pull mirroring for a Github repository
• on GitHub side, create a new branch and make a new commit, pull it via GitLab mirror
• create one more commit in this branch, pull it via GitLab mirror
• squash two previous commits, try to pull it via GitLab mirror

Example Project

• https://gitlab.com/atanayno/pull-mirror-test/
• https://github.com/akindofalex/mirror-test/tree/akindofalex-test-1

What is the current bug behavior?

Pull mirroring will not obtain squashed commit.

What is the expected correct behavior?

Pull mirroring should obtain squashed commit.

Relevant logs and/or screenshots

n/a

Output of checks

This bug happens on GitLab.com

Possible fixes

As a workaround, one can remove the problem branch on the GitLab side and repeat pull mirroring.