Bamboo saplings stick to slime blocks and sticky pistons.
Please see the attached video.

Steps to reproduce (please see the attached video):

1. Place a sticky piston facing north, south, east or west one block above the ground. 
2. Place one slime block in front of the piston
3. Place a bamboo sapling underneath the slime block (on the ground)
4. Power and unpower the piston with a button.
   OR
5. Place a sticky piston facing north, south, east or west on the ground.
6. Place a bamboo sapling in front of the piston.
7. Power and unpower the piston with a button.

Observation:

The bamboo sapling sticks to the slime block or sticky piston.

Expected result:

The bamboo sapling don't stick to the slime block and sticky piston.