$ git clone -n https://src.fedoraproject.org/forks/u2fsdgvkx1/rpms/gcc.git /var/lib/mock/f45-build-350-196/root/chroot_tmpdir/scmroot/gcc
Cloning into '/var/lib/mock/f45-build-350-196/root/chroot_tmpdir/scmroot/gcc'...
$ git fetch origin 33560119a29ebf5d971daae2d5fe751d95789d77:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/forks/u2fsdgvkx1/rpms/gcc
 * [new ref]         33560119a29ebf5d971daae2d5fe751d95789d77 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 3356011 add RVA23 support