What is the package version update policy for stable channels?

For example, python 3.9, which is released on Oct 2020, is still not available on nixos-20.09.
Will nixos-20.09 get python 3.9 some time, or it will stick to 3.8?

On the other hand, aws-vault is still 6.0.0 on 20.09, while on unstable channel the package is 6.2.0. I don’ think there is a reason to stick to 6.0.0.

I’d rather avoid unstable channels because it sounds unsafe for daily use, but nixos-20.09 won’t let me use latest minor version of some packages.

I’d rather avoid unstable channels because it sounds unsafe for daily use, but nixos-20.09 won’t let me use latest minor version of some packages.

Aren’t unexpected changes in the minor versions exactly what is dangerous about unstable?? The idea of providing multiple versions is not too popular because of the many possible combinations with interactions nobody else has tried.

You can mix specific packages from specific snapshots of unstable with the base system from stable (with duplication of dependencies, so yoiu will have two versions of glibc etc.), though.

No idea about specific packages on stable, I just build from the repository checkout and rollback or use old builds of specific packages whenever something breaks.

Packages are typically only updated on stable channels to address bugs and security issues. There are some exceptions, such as web browsers.

Then aws-vault should be updated, 6.1.0 and 6.2.0 only contains bug fixes. 6.2.0 was released on 25 Sep 2020, old enough to be considered stable. Can I request updates on stable channels? GitHub issue template seems to be for unstable channel.

https://github.com/NixOS/nixpkgs/blob/e5ce05cc1eee0b8d890726e9826791ef95c51793/.github/ISSUE_TEMPLATE/out_of_date_package_report.md
https://github.com/99designs/aws-vault/releases

There is no danger on using aws-vault from unstable channel though.

Are they bugs that a user of the package has run into? At any rate, the package maintainer(s) can probably best make that call.

@jonringer also made a video tutorial about backporting changes:

Some of the bugs may affect package users but only in specific condition.

Maybe I could ask for Package maintainer(s) to backport the package. I try learning how to backport a package anyway. Thank you.