$ git clone -n https://src.fedoraproject.org/rpms/rubygems.git /var/lib/mock/f41-build-746426-13355/root/chroot_tmpdir/scmroot/rubygems
Cloning into '/var/lib/mock/f41-build-746426-13355/root/chroot_tmpdir/scmroot/rubygems'...
$ git fetch origin 9dc3880e15cae603955f4f82cd4e0d50d2cf0daa:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygems
 * [new ref]         9dc3880e15cae603955f4f82cd4e0d50d2cf0daa -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 9dc3880 Eliminate use of obsolete %patchN syntax (#2283636)