Submodules to Github Gists appear with the wrong URL

Summary

Git submodules that link to GitHub gists link to the wrong URL on the web UI.

Steps to reproduce

1. git submodule add <paste link of any GitHub Gist>
2. Commit, push
3. Open web UI and click on the link to the new submodule

Example Project

https://gitlab.com/GreatEmerald/gist-submodule-bug-example

What is the current bug behavior?

The link goes to https://github.com/..., which gives a 404.

What is the expected correct behavior?

It should go to https://gist.github.com/... (simply prepending "gist." makes it go to the right place)

Relevant logs and/or screenshots

The .gitmodules file uses the correct URL:

[submodule "2556d79d899f253c46ee830a3b1c5c15"]
        path = 2556d79d899f253c46ee830a3b1c5c15
        url = https://gist.github.com/GreatEmerald/2556d79d899f253c46ee830a3b1c5c15

Output of checks

This bug happens on GitLab.com