$ pytest-2.7
Traceback (most recent call last):
File "/usr/bin/pytest-2.7", line 6, in <module>
from pkg_resources import load_entry_point
File "/usr/lib/python2.7/site-packages/pkg_resources/__init__.py", line 3147, in <module>
@_call_aside
File "/usr/lib/python2.7/site-packages/pkg_resources/__init__.py", line 3131, in _call_aside
f(*args, **kwargs)
File "/usr/lib/python2.7/site-packages/pkg_resources/__init__.py", line 3160, in _initialize_master_working_set
working_set = WorkingSet._build_master()
File "/usr/lib/python2.7/site-packages/pkg_resources/__init__.py", line 666, in _build_master
ws.require(__requires__)
File "/usr/lib/python2.7/site-packages/pkg_resources/__init__.py", line 984, in require
needed = self.resolve(parse_requirements(requirements))
File "/usr/lib/python2.7/site-packages/pkg_resources/__init__.py", line 870, in resolve
raise DistributionNotFound(req, requirers)
pkg_resources.DistributionNotFound: The 'pluggy<0.7,>=0.5' distribution was not found and is required by pytest
etc.