Duke3D: (clipping) autocrouch occurs when shrunk in tight spaces
When moving under a tight space when shrunk, the game now forces Duke into the crouched state, making him move slower.
This started with 744a46f1. (You were right TX, it did break something else!!)
Here's a map to test the behavior. shrinkercrouch.map
Using r9257 you will not be able to make it to the exit by moving straight forward.