[Fixed] [r3297] E3M4 dead end issue extra problematic in ZDoom

[Janizdreg]

As you may know, this E3M4 linedef is basically a (likely erroneous) door switch that monsters can use, which closes the attached sector and blocks the rest of the level if you happen to be on the wrong side when it closes.

In vanilla Doom and most source ports this isn't a huge issue because monsters usually pass the linedef without activating it, as the "door" is in most cases already open when they do. However, in ZDoom the monsters tend to activate the linedef regardless of the sector being open or closed. This is a serious issue at least on UV where the area is filled with monsters, and some of them usually pass and activate the linedef while you fight the horde. Thus if you are unlucky enough to back away into the earlier portion of the level and don't know about the problem, you will get stuck.

[Graf Zahl]

Tell you what: I actually have gotten stuck there way, way back in 1994 or 1995 when source port were a thing of the distant future.
And technically this is a map bug and I'm not really sure what might be different here - if there's something different.

[randi]

Fixed.

[Graf Zahl]

That fix is not good, I believe. It will completely close off the passage from the inside. This is a door for multiplayer purposes. Changing it into a locked door instead of clearing its special is a better solution, I think.

[randi]

Sousou! Refixed.