$ git clone -n https://src.fedoraproject.org/rpms/since.git /var/lib/mock/f45-build-36100-701/root/chroot_tmpdir/scmroot/since
Cloning into '/var/lib/mock/f45-build-36100-701/root/chroot_tmpdir/scmroot/since'...
$ git fetch origin 49a667c0686bb451e9bcc9943f57567224c08c16:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/since
 * [new ref]         49a667c0686bb451e9bcc9943f57567224c08c16 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 49a667c Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild