[0.12.26] Walls can't be build next to biter spawners

[Lukam0s]

You can normally place walls on the corners of biter spawners. But you cant when you build walls on the two other sides of the biter spawner. This description is a little bit vague, check out the file to see what I mean.

[GoldenPorkchop80]

Seems to be some kind of structural value error. Here is what i mean by this:

S = Spawner
W = Wall
| = Wall collision coding.
. = Ignore this

Wall without corner:

............WW
S S S S S S S S W
S S S S S S S S W
S S S S S S S S
S S S S S S S S

OK!

Wall with corner:

.............WWW
S S S S S S S|S|W
S S S S S S S S W
S S S S S S S S
S S S S S S S S

Not good!

Basiclly, it thinks that the wall is intersecting with the spawner when a corner block is made.
I currently have no workaround or solution to this, sorry!
Best of luck!