系统信息： UBUNTU - 16.04 Python 2.7（在全局工作空间中） Python 3.5.4（在虚拟环境中）
描述： 我在全球工作区安装了ROS。现在我正在尝试使用虚拟环境来处理它。
运行命令'pip'，我收到此错误：
Traceback (most recent call last):
File "/usr/lib/python2.7/dist-packages/pip/_vendor/__init__.py", line 33, in vendored
__import__(vendored_name, globals(), locals(), level=0)
ImportError: No module named 'pip._vendor.pkg_resources'
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/home/abhisek/anaconda2/envs/pytorch35/bin/pip", line 7, in <module>
from pip._internal import main
File "/usr/lib/python2.7/dist-packages/pip/__init__.py", line 13, in <module>
from pip.exceptions import InstallationError, CommandError, PipError
File "/usr/lib/python2.7/dist-packages/pip/exceptions.py", line 6, in <module>
from pip._vendor.six import iteritems
File "/usr/lib/python2.7/dist-packages/pip/_vendor/__init__.py", line 75, in <module>
vendored("pkg_resources")
File "/usr/lib/python2.7/dist-packages/pip/_vendor/__init__.py", line 36, in vendored
__import__(modulename, globals(), locals(), level=0)
File "/usr/lib/python2.7/dist-packages/pkg_resources/__init__.py", line 2927, in <module>
@_call_aside
File "/usr/lib/python2.7/dist-packages/pkg_resources/__init__.py", line 2913, in _call_aside
f(*args, **kwargs)
File "/usr/lib/python2.7/dist-packages/pkg_resources/__init__.py", line 2952, in _initialize_master_working_set
add_activation_listener(lambda dist: dist.activate())
File "/usr/lib/python2.7/dist-packages/pkg_resources/__init__.py", line 956, in subscribe
callback(dist)
File "/usr/lib/python2.7/dist-packages/pkg_resources/__init__.py", line 2952, in <lambda>
add_activation_listener(lambda dist: dist.activate())
File "/usr/lib/python2.7/dist-packages/pkg_resources/__init__.py", line 2515, in activate
declare_namespace(pkg)
File "/usr/lib/python2.7/dist-packages/pkg_resources/__init__.py", line 2097, in declare_namespace
_handle_ns(packageName, path_item)
File "/usr/lib/python2.7/dist-packages/pkg_resources/__init__.py", line 2047, in _handle_ns
_rebuild_mod_path(path, packageName, module)
File "/usr/lib/python2.7/dist-packages/pkg_resources/__init__.py", line 2066, in _rebuild_mod_path
orig_path.sort(key=position_in_sys_path)
AttributeError: '_NamespacePath' object has no attribute 'sort'
我尝试过升级setuptools和pip但没有帮助。 我注意到的一件事是它继续指向/usr/lib/python2.7/dist-packages/pip的回溯。但我不知道如何使事情正确。