Simultaneously pressing the W and S keys while controlling a boat propels it forward

Typically, pressing both W and S keys simultaneously results in no movement. This holds true when riding entities like horses, donkeys, mules, skeleton horses, or zombie horses. However, when riding a boat, pressing W and S together moves you forward instead of remaining stationary. This issue emerged in version 16w04a when boat controls were altered to function with W and S keys again. (This was removed in some 1.9 snapshots and then readded.) Before 1.9 boats didn't have this issue. Notably, pressing A and D simultaneously in a boat doesn't cause any movement, as expected.

Steps to reproduce

1. Place a boat
2. Ride the boat
3. Press W and S at simultaniously

Observed outcome: The boat moves forward.
Expected outcome: The boat should remain stationary.