$ git clone -n https://src.fedoraproject.org/rpms/rubygem-mail.git /var/lib/mock/f45-build-35092-693/root/chroot_tmpdir/scmroot/rubygem-mail
Cloning into '/var/lib/mock/f45-build-35092-693/root/chroot_tmpdir/scmroot/rubygem-mail'...
$ git fetch origin 4209066c6e2cbec39cebd6c1d6aa459e1807dade:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-mail
 * [new ref]         4209066c6e2cbec39cebd6c1d6aa459e1807dade -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 4209066 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild