$ git clone -n https://src.fedoraproject.org/rpms/file-roller.git /var/lib/mock/f40-build-1996399-44010/root/chroot_tmpdir/scmroot/file-roller
Cloning into '/var/lib/mock/f40-build-1996399-44010/root/chroot_tmpdir/scmroot/file-roller'...
$ git fetch origin 31e57c9914e85d46c2b0d543547adf08e284bb37:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/file-roller
 * [new ref]         31e57c9914e85d46c2b0d543547adf08e284bb37 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 31e57c9 Update to 43.1