Glitchy mirror if sky with farbox is visible - Nightly builds

[The-Gig]

Hi, I noticed a glitch which happens with current Windows nightly builds (and, although it looks a bit different, also in the Android port, at least on my old S4), while it works correctly with old 0.8.8 binaries.

It looks like that if a sky with a "farbox" (http://toolz.nexuizninjaz.com/shader/shader/section3.htm#3.1) is visible in a mirror, it is drawn very glitchy inside the mirror.

You can test in q3tourney6ish map (http://www.mapraider.com/maps/openarena/free-for-all/5586/q3tourney6ish), which uses skies2/nebula2 shader, but I did some try with some other shader including a farbox such as skies2/nebula and another one, and the result was the same, while "standard" skies were correctly drawn instead. To me it looks like the glitch is somehow related with the presence of a farbox.

Screenshots show comparison of 0.8.8 binaries with 2019-09-29 nightly builds. Windows 10 64 bit with an ATI card.