I was playing around with my water bucket then my teacher called me away and when I came back I was jumping on the stair next to water without pressing space (jump).
To reproduce make water flow next to the stairs and stand halfway in between the FLOWING water and bottom step of stairs.
It can also happen with still water if a move button is held. It also affects non-player entities that extend EntityLivingBase, most notably armor stands.
It also happens when walking into flowing water against a solid block (you'll end up on top of the stone bricks):
[media]Linked issues
is duplicated by 9
MC-11020
Holding forward on a halfslab against a wall with water next to you will make you auto jump.
Resolved
MC-16626
Jumping in water bug/glitch
Resolved
MC-27127
Stair/Slab Water Hop
Resolved
MC-127582
autojump on half_slab
Resolved
MC-147981
Forced jump while crouching on waterlogged slab
Resolved
4 more links
relates to 2
Attachments
Comments 41
31 more comments
Confirmed with a similar set up involving the block above a fence. I will post a screenshot soon.