it involves the "patches-must-be-approved-by-upstream" to still be called Rust clause that Rust inherits from the Mozilla Trademark policy. Its the same policy that led to the creation of IceWeasel/Waterfox etc.

The root issue with Iceweasel was the logo, in my understanding. It was also resolved years ago. Rust does not inherit these problems, and even then, Mozilla will not be holding these trademarks anymore, even though I do not expect our policy will change once ownership changes.

We do also, you know, give permission.

Here is the core of the issue:

https://lwn.net/Articles/118279/

Debian wanted to allow anyone to patch their firefox. Mozilla said OK, but not with our name attached to it.

And this makes sense on some level : No project wants to provide support for someone else's bugs.

For a desktop app it's understandable, but tons of scripts rely on the existence of rustc and cargo binaries. If the fork has to rename it to not-rustc just because it added e.g. gcc support, then that's going to break all the scripts.