pew: broken build

[periklis]

Issue description

building '/nix/store/7xhmjy8hxp340hr2z2qql25c727ppiy1-pew-1.1.2.drv'...
builder for '/nix/store/7xhmjy8hxp340hr2z2qql25c727ppiy1-pew-1.1.2.drv' failed with exit code 1; last 10 log lines:
      raise ValueError('unknown locale: %s' % localename)
  ValueError: unknown locale: UTF-8


  ----------------------------------------------------------------------
  Ran 1 test in 0.000s

  FAILED (errors=1)
  Test failed: <unittest.runner.TextTestResult run=1 errors=1 failures=0>
  error: Test failed: <unittest.runner.TextTestResult run=1 errors=1 failures=0>

cc @berdario

Technical details

 - system: `"x86_64-darwin"`
 - host os: `Darwin 18.0.0, macOS 10.14`
 - multi-user?: `yes`
 - sandbox: `no`
 - version: `nix-env (Nix) 2.1.3`
 - channels(root): `"nixpkgs-18.09pre149107.3878342ef02"`
 - nixpkgs: `/Users/username/path/to/nixpkgs`

[berdario]

Thanks @alyssais 🎉
they fixed it before I even had a chance to look at this! 😄