This regular expression can be used to convert a manually made commit link in Markdown into the plain commit hash, so GitHub (for instance) will automatically display links to commits in places where that's supported, but so you can keep the manual notation in your changelog file in your repository, for example (assuming it's using Markdown).
Using the regular expression from the regex.re file, you would convert the below syntax of a commit link:
[`xxxxxxx`](https://github.com/owner/repo/commit/xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx)