Error when running pypi2nix command

[ns-cweber]

Description

<detailed description of error # Traceback

% pypi2nix --version
% pypi2nix -r requirements.txt
Collecting aenum==2.1.0
  Downloading aenum-2.1.0.tar.gz (95 kB)
  Saved /private/var/folders/3h/fj8x_qcj2w39h7cwqyhnrkgr0000gp/T/tmpyg96gf4_/download/aenum-2.1.0.tar.gz
Collecting aiohttp==3.4.4
  Downloading aiohttp-3.4.4.tar.gz (822 kB)
  Saved /private/var/folders/3h/fj8x_qcj2w39h7cwqyhnrkgr0000gp/T/tmpyg96gf4_/download/aiohttp-3.4.4.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'
Collecting aiohttp-jinja2>=1.1.2
  Downloading aiohttp-jinja2-1.2.0.tar.gz (51 kB)
  Saved /private/var/folders/3h/fj8x_qcj2w39h7cwqyhnrkgr0000gp/T/tmpyg96gf4_/download/aiohttp-jinja2-1.2.0.tar.gz
Collecting aiohttp-swagger==1.0.5
  Downloading aiohttp-swagger-1.0.5.tar.gz (817 kB)
  Saved /private/var/folders/3h/fj8x_qcj2w39h7cwqyhnrkgr0000gp/T/tmpyg96gf4_/download/aiohttp-swagger-1.0.5.tar.gz
Collecting aiopg==0.16.0
  Downloading aiopg-0.16.0.tar.gz (28 kB)
  Saved /private/var/folders/3h/fj8x_qcj2w39h7cwqyhnrkgr0000gp/T/tmpyg96gf4_/download/aiopg-0.16.0.tar.gz
Collecting aioredis<2,>=1.1.0
  Downloading aioredis-1.3.1.tar.gz (155 kB)
  Saved /private/var/folders/3h/fj8x_qcj2w39h7cwqyhnrkgr0000gp/T/tmpyg96gf4_/download/aioredis-1.3.1.tar.gz
Collecting aioredlock==0.3.0
  Downloading aioredlock-0.3.0.tar.gz (8.0 kB)
  Saved /private/var/folders/3h/fj8x_qcj2w39h7cwqyhnrkgr0000gp/T/tmpyg96gf4_/download/aioredlock-0.3.0.tar.gz
Collecting aiotask_context<1,>=0.5.0
  Downloading aiotask_context-0.6.1.tar.gz (5.5 kB)
  Saved /private/var/folders/3h/fj8x_qcj2w39h7cwqyhnrkgr0000gp/T/tmpyg96gf4_/download/aiotask_context-0.6.1.tar.gz
Collecting alembic==0.9.7
  Downloading alembic-0.9.7.tar.gz (1.0 MB)
  Saved /private/var/folders/3h/fj8x_qcj2w39h7cwqyhnrkgr0000gp/T/tmpyg96gf4_/download/alembic-0.9.7.tar.gz
Collecting alooma==0.4.14
  Downloading alooma-0.4.14.tar.gz (16 kB)
  Saved /private/var/folders/3h/fj8x_qcj2w39h7cwqyhnrkgr0000gp/T/tmpyg96gf4_/download/alooma-0.4.14.tar.gz
Collecting ansicolor>=0.2.6
  Downloading ansicolor-0.2.6.tar.gz (6.2 kB)
  Saved /private/var/folders/3h/fj8x_qcj2w39h7cwqyhnrkgr0000gp/T/tmpyg96gf4_/download/ansicolor-0.2.6.tar.gz
Collecting arrow==0.12.1
  Downloading arrow-0.12.1.tar.gz (65 kB)
  Saved /private/var/folders/3h/fj8x_qcj2w39h7cwqyhnrkgr0000gp/T/tmpyg96gf4_/download/arrow-0.12.1.tar.gz
Collecting astor==0.7.1
  Downloading astor-0.7.1.tar.gz (30 kB)
  Saved /private/var/folders/3h/fj8x_qcj2w39h7cwqyhnrkgr0000gp/T/tmpyg96gf4_/download/astor-0.7.1.tar.gz