Remove a failing test
Remove a failing test

OK yes, this is awful, but this is reasonably tested elsewhere and I
need to get this release out. This started failing when I added the
belongs to annotation to `Comment`, as now we're trying to do the
selectable expression hack twice. I need to separate out the joins from
the associations somehow, and this test should just work without
exploding.

cascalheira/diesel,diesel-rs/diesel,mcasper/diesel,sgrif/diesel,mcasper/diesel,cascalheira/diesel,diesel-rs/diesel,sgrif/diesel