The bug

While inside a water stream and against a block ( or 2 blocks ). If the player walks out of the water using aswd, the player jumps without pressing the spacebar. Auto jump is disabled. This works with flowing water of any level and source water.

How to reproduce

1. Place a water source 1 block in the ground.
2. Place a sign next to the water.
3. Get in the water and walk against the side of a block.
4. Then walk out of the water / to the sign while keeping contact with the block.