Duke3D: (clipping) sectors with a sloped floor/ceiling will crush you if the height is less than 3072 units
The height between floor and ceiling without taking into account the slope is 2048 map units. If the player enters this sector in any location (for instance even all the way to the left where there is plenty of vertical space), the player will be crushed regardless of where he entered it.
Here's the above test map to showcase this: slopesquish_bug.map
Surprisingly, this is a vanilla DOS bug that has stuck around all the way into current eduke32.