beam.packages.erlangR20.elixir warning: latin1 encoding vs. utf8

[hauntedhost]

Issue description

When installing latest Elixir with Erlang 20 via beam.packages.erlangR20.elixir, several of these warnings are emitted through the build process:

warning: the VM is running with native name encoding of latin1 which may cause Elixir to malfunction as it expects utf8. Please ensure your locale is set to UTF-8 (which can be verified by running "locale" in your shell)

Steps to reproduce

I'm installing through environment.systemPackages with this configuration.nix (on Vultr FWIW). Though I believe nix-env -i beam.packages.erlangR20.elixir on a new system may be enough to reproduce.

The only way I've gotten the warnings to subside if by specifying this pkgs.lib.overrideDerivation.

Technical details

• System: minimal-18.03pre116572.9824ca6975-x86_64-linux
• Nix version: 1.11.15
• Nixpkgs version: 18.03pre116572.9824ca6975
• Sandboxing enabled: false

[hauntedhost]

/cc: @gleber (by request from /r/NixOS)

[ankhers]

I will look into this.

[gleber]

I see that you have dropped the override. Is this because of these are just harmless warnings?

I've switched to the same nixpkgs and could not reproduce the warnings on Ubuntu:

$ git checkout 9824ca6975
HEAD is now at 9824ca6... caffe: Make 'bin' the first output

$ nix-build -A beam.packages.erlangR20.elixir .
[snip]
/nix/store/05ncr9vibjin9kshwws52ysyyhhz5dgw-elixir-1.5.1

Output is here:
https://pastebin.com/nL7GdDLv

I'll try to reproduce this on NixOS machine now.

[gleber]

I was able to reproduce this on NixOS machine: http://ix.io/AHh

[hauntedhost]

Thanks @gleber 🎉