title: Autolayout center y alignment strange behaviour when setting multiplier
body: <p>I have a helper view with dynamic height in my storyboard, this is a common practice to make layout responsive.</p>
  
  <p>However, something strange happens when I introduce multipliers.</p>
  
  <p>The blue button is aligned center y to the white view on the left:</p>
  
  <p><a href="https://i.stack.imgur.com/9BrZU.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/9BrZU.png" alt="enter image description here"></a></p>
  
  <p>Changing multiplier value into 0.5 should align the button to center of first half of the white view, at least it works this way when aligning to superview. </p>
  
  <p>Instead I end up with sth like this:
  <a href="https://i.stack.imgur.com/rpkh5.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/rpkh5.png" alt="enter image description here"></a></p>
  
  <p>The blue button height is equal to 0.05 times th height of the superview. The white view height is equal to 4 timees the height of the blue button</p>
  
  <p>I have no idea what is the problem here that causes this weird alignment. I suspected it might be something with dynamic height value,  so I tried setting explicit height value but the result was exactly the same.</p>