networking.wireguard...publicKey fails on newlines

[dbeecham]

Describe the bug

If a networking.wireguard.interfaces.<name>.peers.<peer-index>.publicKey contains newlines, e.g. when using = builtins.readFile pubkey, this bit of code

    let
      keyToUnitName = replaceChars
        [ "/" "-"    " "     "+"     "="      ]
        [ "-" "\\x2d" "\\x20" "\\x2b" "\\x3d" ];
      unitName = keyToUnitName publicKey;
      refreshSuffix = optionalString dynamicRefreshEnabled "-refresh";
    in
      "wireguard-${interfaceName}-peer-${unitName}${refreshSuffix}";

in nixos/modules/services/networking/wireguard.nix doesn't substitute the newline, and nix fails with an error like "store path contains illegal character ' '".

Steps To Reproduce

Steps to reproduce the behavior:

1. ...publicKey = "\n"
2. build

Expected behavior

newline is replaced with some useful character

Notify maintainers

@grahamc maybe

[dbeecham]

May be related to NixOS/nix#5466