Windows下升级pip推荐的方式为：

$ python -m pip install --upgrade pip

这样操作却往往会出现下面的错误：

Exception:
Traceback (most recent call last):
  File "D:\Kangbeibei\python_project\datamining-learning\decision_tree\venv\lib\site-packages\pip-9.0.3-py3.6.egg\pip\basecommand.py", line 215, in main
    status = self.run(options, args)
  File "D:\Kangbeibei\python_project\datamining-learning\decision_tree\venv\lib\site-packages\pip-9.0.3-py3.6.egg\pip\commands\install.py", line 342, in run
    prefix=options.prefix_path,
  File "D:\Kangbeibei\python_project\datamining-learning\decision_tree\venv\lib\site-packages\pip-9.0.3-py3.6.egg\pip\req\req_set.py", line 784, in install
    **kwargs
  File "D:\Kangbeibei\python_project\datamining-learning\decision_tree\venv\lib\site-packages\pip-9.0.3-py3.6.egg\pip\req\req_install.py", line 851, in install
    self.move_wheel_files(self.source_dir, root=root, prefix=prefix)
  File "D:\Kangbeibei\python_project\datamining-learning\decision_tree\venv\lib\site-packages\pip-9.0.3-py3.6.egg\pip\req\req_install.py", line 1064, in move_wheel_files
    isolated=self.isolated,
  File "D:\Kangbeibei\python_project\datamining-learning\decision_tree\venv\lib\site-packages\pip-9.0.3-py3.6.egg\pip\wheel.py", line 462, in move_wheel_files
    generated.extend(maker.make(spec))
  File "D:\Kangbeibei\python_project\datamining-learning\decision_tree\venv\lib\site-packages\pip-9.0.3-py3.6.egg\pip\_vendor\distlib\scripts.py", line 372, in make
    self._make_script(entry, filenames, options=options)
  File "D:\Kangbeibei\python_project\datamining-learning\decision_tree\venv\lib\site-packages\pip-9.0.3-py3.6.egg\pip\_vendor\distlib\scripts.py", line 276, in _make_script
    self._write_script(scriptnames, shebang, script, filenames, ext)
  File "D:\Kangbeibei\python_project\datamining-learning\decision_tree\venv\lib\site-packages\pip-9.0.3-py3.6.egg\pip\_vendor\distlib\scripts.py", line 212, in _write_script
    launcher = self._get_launcher(‘t‘)
  File "D:\Kangbeibei\python_project\datamining-learning\decision_tree\venv\lib\site-packages\pip-9.0.3-py3.6.egg\pip\_vendor\distlib\scripts.py", line 351, in _get_launcher
    result = finder(distlib_package).find(name).bytes
AttributeError: ‘NoneType‘ object has no attribute ‘bytes‘

可以采用下面的安装方式解决：

$ python -m pip install -U --force-reinstall pip