$ git clone -n https://src.fedoraproject.org/rpms/rubygem-cairo-gobject.git /var/lib/mock/f41-build-740618-13309/root/chroot_tmpdir/scmroot/rubygem-cairo-gobject
Cloning into '/var/lib/mock/f41-build-740618-13309/root/chroot_tmpdir/scmroot/rubygem-cairo-gobject'...
$ git fetch origin 905a813664f70984d313be27d587ea849af30bb5:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-cairo-gobject
 * [new ref]         905a813664f70984d313be27d587ea849af30bb5 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 905a813 4.2.2 entry