Python cryptography, Rust, and Gentoo

The reality in Debian is that due to the huge number of security holes that web browsers acrete and the fact that even the LTS release cycles of firefox are much shorter than those of a stable release they are practically forced to upgrade to new release series of firefox within a stable release.

Before firefox/thunderbird started using rust, this wasn't a huge problem, the firefox package could be updated largely independently of everything else. Nowadays though, a new release series of firefox basically means a new release of rustc.

And that breaks things. Sure the rustc developers have defined a stable subset, but a bunch of crates depend on less stable features. Some of this through the officially endorsed "feature gates" mechanism, others through a certain flag that is not supposed to be used by user code but is anyway that lets you use "nightly" features on a stable compiler.