Sticky piston break unmovable blocks, such as saplings, crops, leaves, liquids, melons and pumpkins when pulled

Sticky pistons break Melon and Pumpkin blocks when pulled.

Steps to reproduce:

• Power a sticky piston
• Place Melon or Pumpkin in front of the piston
• Un-Power piston

That behaviour is different compared to 14w17a or 1.7.9, see screenshots.