Fixed [2.1.14] Enemies Can Clip off of Ledges if Left Unattended

[Zubat]

I was in the middle of a ring run in Record Attack, and I came back through the stage to find this...

Spoiler

I went onto IRC before submitting this, and here's what happened (irrelevant info removed):

<Zubat> I was trying to get all the rings in THZ2
<Zubat> and I saw this
<Zubat> http://gfycat.com/BrightHotAmmonite
<toaster> Oh
<toaster> I've come across that bug in SRB2 2.1.8 as well
<toaster> badniks using A_Chase going off ledges somehow
<toaster> it happens all over and i can never consistently reproduce it
<toaster> there is one piece of information i can provide
<toaster> i believe it involves going close to the badnik's location, then going far away, then coming back and seeing the badnik on the ledge below

 

[Monster Iestyn]

The actual problem behind THIS bug, as I found through testing a number of months back, was one of the diagonal walls surrounding the goop pool in question having badly generated blockmap, and thus anything moving into would fall down slightly inside it unexpectedly (not just to us, but to the game code too - resulting in, yes, Spring Shells falling into goop).

As of 2.1.14 this appears to actually be fixed now, presumably because of RedEnchilada's fixes to blockmap generating to prevent stuff getting stuck in walls. Here, have a gif of a Spring Shell crawling against the original guilty area in question to prove so: