When using a resource pack with a custom Mojang logo, it does not work. It only shows the default Mojang logo. Watching the game output as the game starts, I see that it says "Created: 1024x512 textures-atlas" after the Mojang logo appears, which may be the issue. If the textures-atlas were created before the Mojang screen loaded, then it would work properly.
This bug does not occur in the OptiFine client. I think the Optifine devs fixed this bug. But Mojang hasn't fixed this bug for their original client. Please fix it, I like using a cyan Mojang logo which I put in my resource pack!
Also, this bug has been around for a long time, but I think nobody has addressed it because they think that this bug is intended.
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Comments 2
It would be nice if Mojang included multiple logos in the game, each at different (higher) resolutions, and if there were a way to change to color of the logo, using a logo.mcmeta file. With the file you can customize the resolution of the logo, and the color of the logo. It wouldn't be too hard to implement.
Not a bug.