[2.2.15] Really long sectors have distorted sidedef texture(s) in Software mode
I was able to figure this out because I was trying to crack what exactly was causing #1327 to happen. If you have a really long uninterrupted sector (the one in the example WAD and GIF is roughly over 20k fracunits on its longest side), its sidedef texture(s) will look stretched and distorted in Software mode.
The above GIF uses an example map I created trying to replicate the issue. I have linked it below as well.