$ git clone -n https://src.fedoraproject.org/rpms/perl-Math-Derivative.git /var/lib/mock/f45-build-24685-605/root/chroot_tmpdir/scmroot/perl-Math-Derivative
Cloning into '/var/lib/mock/f45-build-24685-605/root/chroot_tmpdir/scmroot/perl-Math-Derivative'...
$ git fetch origin ed107f0ba6e5f9d9e30e1e0ab160927d65910213:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/perl-Math-Derivative
 * [new ref]         ed107f0ba6e5f9d9e30e1e0ab160927d65910213 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at ed107f0 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild