我的笔记本电脑中有最新版本的 pip。当我使用 pip 安装任何模块时，我总是收到此错误。
Traceback (most recent call last):
File "/usr/local/bin/pip", line 6, in <module>
from pkg_resources import load_entry_point
File "/usr/local/lib/python2.7/site-
packages/pkg_resources/__init__.py", line 3195, in <module>
@_call_aside
File "/usr/local/lib/python2.7/site-
packages/pkg_resources/__init__.py", line 3179, in _call_aside
f(*args, **kwargs)
File "/usr/local/lib/python2.7/site-p
packages/pkg_resources/__init__.py", line 3208, in _
initialize_master_working_set
working_set = WorkingSet._build_master()
File "/usr/local/lib/python2.7/site-
packages/pkg_resources/__init__.py", line 681, in _build_master
ws.require(__requires__)
File "/usr/local/lib/python2.7/site-
packages/pkg_resources/__init__.py", line 999, in require
needed = self.resolve(parse_requirements(requirements))
File "/usr/local/lib/python2.7/site-
packages/pkg_resources/__init__.py", line 885, in resolve
raise DistributionNotFound(req, requirers)
pkg_resources.DistributionNotFound: The 'pip==9.0.3' distribution was …pip ×1