Newlib's git repository
Because I had quite the time finding it when I wanted to submit a patch to newlib, there’s a git mirror of the canonical CVS repository for newlib, which all the patches I saw on the mailing list were based off of. Maybe somebody else looking for it will find this note useful:
git clone git://sourceware.org/git/newlib.git
See also: the original mailing list announcement of the mirror’s availability.