Bodo Eggert

The resource pack has the correct, one-slot image at the location where the one-slot dialog is supposed to be. Expecting a two-slot image from the same location is wrong, the resource pack cannot be "fixed" to do both.

http://en.wikipedia.org/wiki/Software_bug

"A software bug is an error, flaw, failure, or fault in a computer program or system that causes it to produce an incorrect or unexpected result, or to behave in unintended ways."

a) Intended and correct behavior is displaying a two-slot dialog window. Actual result is one slot.
b) Working correctly with old resource packs without them being modified is an obvious design goal. (It was since Dinnerbone still worked at CraftBukkit.)

So is there a reasoning why this wouldn't be a bug?

Besides that, MJ did change the interface in a compatible way when they introduced the new skin system, therefore I conclude that would like to fix this by changing that one line of code.

Because I'd be playing on a server using MC 1.7, a local map using MC 1.8 and also I'd be testing MC snapshots while also having nice eye-candy.

I have to disagree because the whole point of having resource packs and the API instead of old texture packs is not having to wait for an updated pack after a MC update (or to be able to use the same resource pack on a range of MC versions).

Off cause it did persist.

Besides that, breaking compatibility to still-supported debian verisons would still be a bug.

14w04a: Does not happen anymore (Tested with seed/cords from first screenshot)

Sorry, this bugtracker did not seem to do anything on "commit" in opera. It's differently incompatible with Debian Oldstable's firefox, too. ((And this old Firefox is incompatible with different color schemes, which I need because my eyes really hurt after looking at white screens for too long. I'm typing blind unless I select all. And if you're curios why I use oldstable, later versions of Debian don't work with my still quite new mainboard (broken ACPI) )).

I had the impression the current resource pack format was supposed to be stable. It's supposed to be able to contain mods right now, and the API is not nearly done. The old texture packs were incompatible with new features, you had no chance but to upgrade the format and the new packs obviously weren't supposed to be compatible.

(And as you might guess, I very much think breaking old/uncommon setups for no good reason is a bad idea ... )

This is not a feature request. This is an incompatibility between MC 1.8 and existing resource packs, and vice versa. It will show a one-slot-dialog graphic for a two-slot-interface. THIS IS A BUG.
You can't design resource packs to be compatible with both versions, but MC is designed to load both versions and not designed to be configured differently per version (although there is a workaround).

Still happens on 13w39b

Why do you think lava not going away for days might be intentional? Did anybody from mojang officially state that?

And even if they did, that would still be insane, therefore changing that behavior is at least a valid feature request. (As you can read above, it is an obvious programming error, but you need to understand code in order to recognize that.)