title: ActiveRecord appends 'AND (1=0)' to end of queries
body: <p>I've been playing around in the rails console trying to get things to work, and I notice that one of my queries keeps returning nil when it shouldn't.  Upon looking at the generated SQL query I notice that it has <code>AND (1=0)</code> appended to it each time.  This is kind of annoying, and I'm not sure why it's doing this.</p>
  <p><em>Note:</em> Using the actable gem.</p>
  <p>Steps to reproduce:</p>
  <p>(After connecting to tables in rails console)</p>
  <pre><code>2.1.2 :xxxx &gt; @parent = Parent.take
  Parent Load (38.1ms)  SELECT  `parents`.* FROM `parents`  LIMIT 1
   =&gt; #&lt;Parent id: 37, ...&gt;
  
  2.1.2 :xxxx &gt; @child = Child.where(id: @parent.actable_id)
  SQL (0.7ms)  SELECT `childs`.`id` AS t0_r0, `childs`.`attribute` AS t0_r1, FROM `childs`
  ...
  LEFT OUTER JOIN `parents` ON `parents`.`actable_id` = `childs`.`id` AND `parents`.`actable_type` = 'child type' WHERE `childs`.`id` = 20 AND (1=0)
   =&gt; #&lt;ActiveRecord::Relation []&gt;
  </code></pre>
  <p>Why is this happening? How do I make it stop?</p>