we ve been using ``` where("0 = 1")``` in many places in katello code. Its a way to say run this query and return no rows. 
In this case we want some thing like
```
if katello_mode
  run its logic
else
  make the query return no rows
end
```

There may be a nicer way and will be good to see if there exists one, but we ve been using this convention forever afaik