$ git clone -n https://src.fedoraproject.org/rpms/cmatrix.git /var/lib/mock/f39-build-1845215-42082/root/chroot_tmpdir/scmroot/cmatrix
Cloning into '/var/lib/mock/f39-build-1845215-42082/root/chroot_tmpdir/scmroot/cmatrix'...
$ git fetch origin f2f7d1ba7b020fb62b682923b7ca80df63749b27:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/cmatrix
 * [new ref]         f2f7d1ba7b020fb62b682923b7ca80df63749b27 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at f2f7d1b migrated to SPDX license