$ git clone -n https://src.fedoraproject.org/rpms/rubygem-cairo-gobject.git /var/lib/mock/f41-build-857132-167917/root/chroot_tmpdir/scmroot/rubygem-cairo-gobject
Cloning into '/var/lib/mock/f41-build-857132-167917/root/chroot_tmpdir/scmroot/rubygem-cairo-gobject'...
$ git fetch origin adaad9b17e61ed4a19161536e1ad9df63109715c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-cairo-gobject
 * [new ref]         adaad9b17e61ed4a19161536e1ad9df63109715c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at adaad9b 4.2.4 entry