$ git clone -n https://src.fedoraproject.org/rpms/rubygem-regexp_parser.git /var/lib/mock/f45-build-35263-694/root/chroot_tmpdir/scmroot/rubygem-regexp_parser
Cloning into '/var/lib/mock/f45-build-35263-694/root/chroot_tmpdir/scmroot/rubygem-regexp_parser'...
$ git fetch origin cf48a8789e88108cf930352cb9cf5013289f7161:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-regexp_parser
 * [new ref]         cf48a8789e88108cf930352cb9cf5013289f7161 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at cf48a87 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild