This is just !102 (merged) redone, the fix seems to have been lost when doing !116 (merged).
Basically, netradiant was displaying wrongly some transparent textures, those with cheap transparency stored in tRNS.
If your some of your translucent png textures looked like this, you were facing this bug:
The PNG specification has more than 15 format variants, about 9 for format with transparency. The compression efficiency of PNG does not really comes from the compression algorithm which seems to not have any picture-specific algorithm (it's just zlib) but from that panel of format variants an optimizer can leverage.
As seen on the screenshot, I made a special map to test those PNG formats, the map can be found there: https://github.com/UnvanquishedAssets/UnvanquishedTestAssets/tree/master/src/map-test-pngalpha_src.dpkdir
The map can also be used to test PNG support in q3map2, and a game renderer.
Thanks to alphashadow feature, we can test q3map2 is reading properly the PNG alpha channel by casting shadows this way:
To test the engine, and help to test q3map2, the textures are displayed two time in game, with a proper blend (true alpha channel), or with a GE128 function to look like what q3map2 proceeds for real when casting shadows:
