Python3 virtualenv安装异常

Question

我尝试过：

$sudo pip install virtualenv

$pip install virtualenv

$sudo pip3 install -U virtualenv

但是我遇到了这个异常：

Exception:
Traceback (most recent call last):
File "/usr/lib/python2.7/dist- packages/pip/basecommand. py',  line 215, in main
status = self.run(options, args)
File '/usr/lib/python2.7/dist-packages/pip/wheel. py", line 749, in build
self.requirement_set.prepare_files(self.finder)