Many users have reported problems that stem from having an unclean
working tree. To that end, I've written a guix-clean script which should
help reset the working tree while respecting user-specified precious
directories.
Precious directories, such as:
- SOURCES_PATH
- BASE_CACHE
- SDK_PATH
- OUTDIR
Should be preserved when cleaning the working tree, and are thus
recorded in ./contrib/guix/var/precious_dirs.
The ./contrib/guix/guix-clean script is able to parse that file and make
sure to avoid them when cleaning out the working tree.
