$ git clone -n https://src.fedoraproject.org/rpms/gcc.git /var/lib/mock/f42-build-side-1-3533467-46361/root/chroot_tmpdir/scmroot/gcc
Cloning into '/var/lib/mock/f42-build-side-1-3533467-46361/root/chroot_tmpdir/scmroot/gcc'...
$ git fetch origin 789e812095a434506b600634b38d9051322ee969:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gcc
 * [new ref]         789e812095a434506b600634b38d9051322ee969 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 789e812 15.1.1-2