Descriptive Problem Summary:
Collision detection fails in certain conditions: http://i.imgur.com/LbH9dRR.gif

Requires pixel movement:
From the south, you can enter dense tiles between their east and west edges.
From the east, you can enter dense tiles below their north edge.

Expected Results:
Can't enter dense stuff.

Actual Results:
Can enter dense stuff.

Does the problem occur:
Every time? Or how often? v
In other games? yes (first noticed in Epoch, also occurs in basic test projects)
In other user accounts? yes
On other computers? yes

Did the problem NOT occur in any earlier versions? If so, what was the last version that worked? (Visit http://www.byond.com/download/build to download old versions for testing.)
This bug is new to 1291.