$ git clone -n https://src.fedoraproject.org/rpms/tucnak.git /var/lib/mock/f39-build-2196669-51595/root/chroot_tmpdir/scmroot/tucnak
Cloning into '/var/lib/mock/f39-build-2196669-51595/root/chroot_tmpdir/scmroot/tucnak'...
$ git fetch origin 623322a2be9521a4f805f4b9c66cb826ecc554a5:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/tucnak
 * [new ref]         623322a2be9521a4f805f4b9c66cb826ecc554a5 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 623322a New version