Fabricweight is a personal tool to create git patch based forks of projects. It is not intended to be used by others, but feel free to do whatever you want with it(keeping in mind the MIT license).
It support forking of forks. In the case of Minecraft mods, this means the 1.16.5 branch can be a fork of the 1.17.1 branch, which can be a fork of the 1.18.2 branch(and so on).
This project is inspired by paperweight and spigots buildtools. But these tools are way too complicated for my needs, and too specific to their project.
Create a file called repo with the git url of the project you want to fork. Then create a second file called sha with the commit hash of the commit you want to fork from. Added to that, an empty directory called patches. Running java -jar fabricweight.jar patch will download the project, and setup a workspace folder. Inside this folder, you can edit the code as you want. When you are done, commit your changed, and run java -jar fabricweight.jar rb to create the patch files in the patches folder. At any later point(after changing the sha for example), you can run java -jar fabricweight.jar patch again to update the workspace folder to the new commit. workspace and upstream should be in your .gitignore.