$ git clone -n https://src.fedoraproject.org/forks/kkleine/rpms/llvm.git /var/lib/mock/f43-build-61066432-6588463/root/chroot_tmpdir/scmroot/llvm
Cloning into '/var/lib/mock/f43-build-61066432-6588463/root/chroot_tmpdir/scmroot/llvm'...
$ git fetch origin 99c8ddad7bc1b5126d6845ab550d6e3a3a8d03fa:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/forks/kkleine/rpms/llvm
 * [new ref]         99c8ddad7bc1b5126d6845ab550d6e3a3a8d03fa -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 99c8dda $ pyprojectize llvm.spec