$ git clone -n https://src.fedoraproject.org/rpms/gnome-user-docs.git /var/lib/mock/f40-build-2593401-62709/root/chroot_tmpdir/scmroot/gnome-user-docs
Cloning into '/var/lib/mock/f40-build-2593401-62709/root/chroot_tmpdir/scmroot/gnome-user-docs'...
$ git fetch origin b6e9b2e5f30fea439e3c21d9cb1bbcfd5f63819e:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gnome-user-docs
 * [new ref]         b6e9b2e5f30fea439e3c21d9cb1bbcfd5f63819e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b6e9b2e Update to 46.0