Players are able to fly when using lift 2 times

[dudullle]

How to reproduce :

• Build an elevator with 2 floors
• Use the elevator to go down AND up (stay right clicked to restart the elevator)
  Thats all, now you can fly.

[ChanceSD]

This bug is still happening on Lift v63, not sure how to reproduce yet but i believe it's by adding stairs above the lift.