I have a script somewhere laying around which does something similar for Gentoo: You give it a package and it will download and prepare it to some directory, th

I have a script somewhere laying around which does something similar for Gentoo: You give it a package and it will download and prepare it to some directory, then let you edit it, then compile it (via the Gentoo ebuild) and test it and you can repeat those last steps until you have fixed/changed what you wanted to do. And then it will return a final patch in the end. I thought this was quite useful. I made quite a few patches this way and was very productive using this script (in some cases, it took me only about 2-5 minutes to prepare a patch if the fix was easy). Though, the script was very hacky and it still often needed some hand-work to be made. I asked some Gentoo developers if there might want to make a full project out of this (because I thought that this might be a useful and important thing) but nobody really was interested.