$ git clone -n https://src.fedoraproject.org/rpms/synthv1.git /var/lib/mock/f45-build-36739-707/root/chroot_tmpdir/scmroot/synthv1
Cloning into '/var/lib/mock/f45-build-36739-707/root/chroot_tmpdir/scmroot/synthv1'...
$ git fetch origin 82eca1cf40b6a8e9b78c033018ddfa5ae7ef1dbf:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/synthv1
 * [new ref]         82eca1cf40b6a8e9b78c033018ddfa5ae7ef1dbf -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 82eca1c Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild