David F-S
Comments
This happens when you are using an options.txt file that says there should be a higher chunk render range than what 1.7.10 supports. (MC 1.8+ support higher chunk render ranges - downgrading can be the cause.)
I retract my previous statement that this bug doesn't effect anything in vanilla. I thought it didn't, but I realized I was mistaken as I became more intimate with the bug's hidden details.
I wrote a simple mod to highlight the locations it manifests in - it makes the entire world an Extreme Hills biome, disables snow tile placement, and places an orange stained clay block directly under the places that have a temperature of exactly 0.15F. After generating the world, I shut down my game and loaded it back up in vanilla.
http://imgur.com/a/9dVSK
The first picture is an aerial view of the effected block locations (at least in Extreme Hills) while the second picture is of the rain falling (without my worldgen mod, taken in the latest snapshot - 16w05b).
If you want a copy of the world to check out for yourself, I still have it. I forgot to disable mineshafts, but it's still easy to check and verify that I'm showing this in pure vanilla and without command blocks.
With this bug, rain animation and audio is played, yet snow tiles form.
To make fixing it as simple a process as possible, these are all of them in 16w05a:
>= .15f is not freezing
bne.p()V (source line 1399; weather/shader rendering class, smoke and rain particles)
bne.c(F)V (source line 1500; weather/shader rendering class, rain/snow rendering)
< .15f is freezing
aka.h(Lahq;Lcj;)V (source line 198)
aid.b(Lahq;Ljava/util/Random;Latd;IID)V (source line 302; base biome class, used for worldgen)
> .15f is not freezing
ahq.e(Lcj;Z)Z (source line 2030; base world class, can block freeze at location)
ahq.f(Lcj;Z)Z (source line 2058; base world class, can it snow at location)
What more can I do to help get this fixed? It's a pathetically simple problem that would only take moments to correct, and I've even pointed out where in the code it's coming from (down to the line numbers in the source files, at that. I've even described what the classes are for, so that it's even not necessary to look through obfuscation logs). What else would help get this perfectly valid bug finally fixed?