Original issue: #17322 (closed). Original PR: #18398.
Honestly, this one is more pain than it's worth. Looking back, the file was originally added because I had left a comment in the variables file that you could copy-pasta some lines into that file for easier customization. I don't think that's a helpful way forward for a few reason:
- It's been brought up in so many issues.
- We flipped how it's used, by changing the import order (and then back again) after it screwed up some other stuff.
- In the current implementation, you cannot use other variables in the custom file—only copy-paste and change the values of existing ones. So, for example, you cannot add
$my-new-var: $blue.
Nuking it in favor of relying on imports from package manager directories (where you're most likely to be using source Sass files) and manual forks of the project.