$ git clone -n https://src.fedoraproject.org/rpms/rubygem-activesupport.git /var/lib/mock/f45-build-34781-691/root/chroot_tmpdir/scmroot/rubygem-activesupport
Cloning into '/var/lib/mock/f45-build-34781-691/root/chroot_tmpdir/scmroot/rubygem-activesupport'...
$ git fetch origin cf9d8952d1a63322ea25ddf503c356c7df4747e2:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-activesupport
 * [new ref]         cf9d8952d1a63322ea25ddf503c356c7df4747e2 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at cf9d895 Update to Active Support 8.1.3.1.