recent update to pkgsrc -current breaks py-certbot

[Roy Marples <roy%marples.name@localhost>]

$ certbot
Traceback (most recent call last):
  File "/usr/pkg/bin/certbot", line 6, in <module>
    from pkg_resources import load_entry_point
  File "/usr/pkg/lib/python2.7/site-packages/pkg_resources/__init__.py",
line 3036, in <module>
    @_call_aside
  File "/usr/pkg/lib/python2.7/site-packages/pkg_resources/__init__.py",
line 3020, in _call_aside
    f(*args, **kwargs)
  File "/usr/pkg/lib/python2.7/site-packages/pkg_resources/__init__.py",
line 3049, in _initialize_master_working_set
    working_set = WorkingSet._build_master()
  File "/usr/pkg/lib/python2.7/site-packages/pkg_resources/__init__.py",
line 654, in _build_master
    ws.require(__requires__)
  File "/usr/pkg/lib/python2.7/site-packages/pkg_resources/__init__.py",
line 968, in require
    needed = self.resolve(parse_requirements(requirements))
  File "/usr/pkg/lib/python2.7/site-packages/pkg_resources/__init__.py",
line 854, in resolve
    raise DistributionNotFound(req, requirers)
pkg_resources.DistributionNotFound: The 'argparse' distribution was not
found and is required by certbot

I don't know anything about python to work out why this no longer works.

Roy