Ladder/Vine Can Trigger Flight in Creative

If a player in Creative mode stands against a ladder that doesn't have a bottom ladder, and then holds down the jump key, they enter flight mode.

Steps to Reproduce:

1. Create a Creative world on a superflat

2. Build a two block high pillar

3. Place a ladder on the top block

4. Stand against the pillar

5. Hold down the jump key

6. Observe how you enter flight mode

Expected Result:

The player climbs the ladder normally.

Actual Result:

The player enters flight mode.