$ git clone -n https://src.fedoraproject.org/rpms/grepmail.git /var/lib/mock/f45-build-13051-446/root/chroot_tmpdir/scmroot/grepmail
Cloning into '/var/lib/mock/f45-build-13051-446/root/chroot_tmpdir/scmroot/grepmail'...
$ git fetch origin 0beb851d639852fa91833348d8d001dd817d1aa7:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/grepmail
 * [new ref]         0beb851d639852fa91833348d8d001dd817d1aa7 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 0beb851 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild