python35: remove

[jonringer]

Motivation for this change

It's EOL soon, and should be removed before 20.09

closes: #95272

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS linux)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.

$ nix-env -f /home/jon/.cache/nixpkgs-review/pr-95305/nixpkgs -qaP --xml --out-path --show-trace --meta
2 packages removed:
python3 (†3.5.9) python3 (†3.5.9)

Nothing changed
https://github.com/NixOS/nixpkgs/pull/95305
$ nix-shell /home/jon/.cache/nixpkgs-review/pr-95305/shell.nix

[FRidh]

I was hoping to get the final patch release in before removing it, so anyone that would be interested in it could easily cherry-pick it or refer to a Nixpkgs release with it. But, the release is delayed and I don't consider it that important either.

[jonringer]

I'll leave this open for a while longer so other can comment, but those are my feelings as well

[bhipple]

If I were you I'd just nuke it now @FRidh. Anyone maintaining a fork w/ a long-lived py 3.5 should be sophisticated enough to bump it to the last 3.5.X patch themselves if they're really keen on it.

Though the commitment to top it off and see it through to the end is admirable.

[jonringer]

according to the original PEP, https://www.python.org/dev/peps/pep-0478/ , the final release was meant to be out almost a month ago, I don't think we should hold our breath.

Also a lot of "core" packages, that you want to bring in through nixpkgs (E.g. pandas), no longer build.

Not to mention that 0 caching makes it very painful to use this package set.

[jonringer]

I could add it to my NUR, and we can have a foot note in the docs . But I would like to discourage people from using it in general