Error when running pypi2nix command to generate derivation xonsh

[jnoortheen]

Thanks for this great tool. I am new to nix ecosystem and struggling to move tools I used on my arch system. This is the error I got when trying to create derivation for xonsh.

Description

<detailed description of error # Traceback

% pypi2nix --version
 2.0.4

% pypi2nix -e xonsh
Collecting xonsh
  Downloading xonsh-0.9.18.tar.gz (976 kB)
  Saved /tmp/tmp1zscbj_8/download/xonsh-0.9.18.tar.gz
  Installing build dependencies: started
  Installing build dependencies: finished with status 'done'
  Getting requirements to build wheel: started
  Getting requirements to build wheel: finished with status 'done'
    Preparing wheel metadata: started
    Preparing wheel metadata: finished with status 'done'
Successfully downloaded xonsh
Looking in links: file:///tmp/tmp1zscbj_8/download
Processing /tmp/tmp1zscbj_8/download/xonsh-0.9.18.tar.gz
  Installing build dependencies: started
  Installing build dependencies: finished with status 'error'

the above auto generated message doesn't include the traceback. Here is the full error