Ubuntu 16.04.04。因為從Ubuntu 16.04.03開始（之前版本沒問題的）pip3 install命令必須使用sudo或su才能安裝，所以我現在已經將$home/.local/bin加入path，并使用pip3 install *** --user來安裝。
最近重做系統(tǒng)，安裝theano的時候發(fā)現必須安裝libgpuarray：有sudo make install和python setup.py install --user命令。
隨后，現在發(fā)現，無論是pip3 --version還是pip3 install [--user]，都必須使用su權限才可以（sudo也不行），否則錯誤如下：

Traceback (most recent call last):
  File "/usr/lib/python3/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 "/usr/bin/pip3", line 9, in <module>
    from pip import main
  File "/usr/lib/python3/dist-packages/pip/__init__.py", line 13, in <module>
    from pip.exceptions import InstallationError, CommandError, PipError
  File "/usr/lib/python3/dist-packages/pip/exceptions.py", line 6, in <module>
    from pip._vendor.six import iteritems
  File "/usr/lib/python3/dist-packages/pip/_vendor/__init__.py", line 75, in <module>
    vendored("pkg_resources")
  File "/usr/lib/python3/dist-packages/pip/_vendor/__init__.py", line 36, in vendored
    __import__(modulename, globals(), locals(), level=0)
  File "<frozen importlib._bootstrap>", line 969, in _find_and_load
  File "<frozen importlib._bootstrap>", line 958, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 664, in _load_unlocked
  File "<frozen importlib._bootstrap>", line 634, in _load_backward_compatible
  File "/usr/share/python-wheels/pkg_resources-0.0.0-py2.py3-none-any.whl/pkg_resources/__init__.py", line 2927, in <module>
  File "/usr/share/python-wheels/pkg_resources-0.0.0-py2.py3-none-any.whl/pkg_resources/__init__.py", line 2913, in _call_aside
  File "/usr/share/python-wheels/pkg_resources-0.0.0-py2.py3-none-any.whl/pkg_resources/__init__.py", line 2952, in _initialize_master_working_set
  File "/usr/share/python-wheels/pkg_resources-0.0.0-py2.py3-none-any.whl/pkg_resources/__init__.py", line 956, in subscribe
  File "/usr/share/python-wheels/pkg_resources-0.0.0-py2.py3-none-any.whl/pkg_resources/__init__.py", line 2952, in <lambda>
  File "/usr/share/python-wheels/pkg_resources-0.0.0-py2.py3-none-any.whl/pkg_resources/__init__.py", line 2515, in activate
  File "/usr/share/python-wheels/pkg_resources-0.0.0-py2.py3-none-any.whl/pkg_resources/__init__.py", line 2097, in declare_namespace
  File "/usr/share/python-wheels/pkg_resources-0.0.0-py2.py3-none-any.whl/pkg_resources/__init__.py", line 2047, in _handle_ns
  File "/usr/share/python-wheels/pkg_resources-0.0.0-py2.py3-none-any.whl/pkg_resources/__init__.py", line 2066, in _rebuild_mod_path
AttributeError: '_NamespacePath' object has no attribute 'sort'

請問如何解決？