title: Is lowerAngleLimit on SKPhysicsJointPin broken?
body: <p>I have never gotten the upper/lower angle limits to work properly on SKPhysicsJointPin objects, and I think I've finally figured out why:  if the lowerAngleLimit is set to a negative value, it breaks every time.  It only works correctly with positive values.</p>
  
  <p>For example, say I set this 90º pin:</p>
  
  <pre><code>    pin.lowerAngleLimit = -PI/2;
      pin.upperAngleLimit = 0;
  </code></pre>
  
  <p>Now I'll make the sprite rotate slowly towards that lower limit.  The instant it hits -90º it will suddenly <em>zoom</em> the sprite the long way around back to 0º.  It will never pin at -90º.  It doesn't matter what negative value I try, -1.0 does the exact same thing.  It appears to be a bug in SpriteKit.  Has anyone else gotten this to work, or found an workaround?</p>