$ git clone -n https://src.fedoraproject.org/rpms/rubygem-mime-types-data.git /var/lib/mock/f45-build-35102-693/root/chroot_tmpdir/scmroot/rubygem-mime-types-data
Cloning into '/var/lib/mock/f45-build-35102-693/root/chroot_tmpdir/scmroot/rubygem-mime-types-data'...
$ git fetch origin de7d04739950efda4c5707539fa99aff4a86c915:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-mime-types-data
 * [new ref]         de7d04739950efda4c5707539fa99aff4a86c915 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at de7d047 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild