Slime blocks and sticky pistons stick to bamboo saplings

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.