Fix "can't find easy_install executable [Errno 2]" in virtualenv(see: http://blog.ikraftsoft.com/post/1397277718/fix-cant-find-easy-install-executable-virtualenv)

The Error

$ mkvirtualenv test
New python executable in ./bin/python
Installing distribute....................................................................................................................................done.
  Complete output from command /home/mir/test/bin/python /home/mir/test/bin/easy_install /usr/share/python-virtualenv/p...ar.gz:
  /home/mir/test/bin/python: can't open file '/home/mir/test/bin/easy_install': [Errno 2] No such file or directory
----------------------------------------
Traceback (most recent call last):
  File "/usr/bin/virtualenv", line 3, in 
    virtualenv.main()
  File "/usr/lib/pymodules/python2.6/virtualenv.py", line 534, in main
    use_distribute=options.use_distribute)
  File "/usr/lib/pymodules/python2.6/virtualenv.py", line 626, in create_environment
    install_pip(py_executable)
  File "/usr/lib/pymodules/python2.6/virtualenv.py", line 391, in install_pip
    filter_stdout=_filter_setup)
  File "/usr/lib/pymodules/python2.6/virtualenv.py", line 595, in call_subprocess
    % (cmd_desc, proc.returncode))
OSError: Command /home/mir/test/bin/python /home/mir/test/bin/easy_install /usr/share/python-virtualenv/p...ar.gz failed with error code 2

The solution

$ sudo pip install pip --upgrade                   # Upgrade pip
$ sudo pip  install virtualenv --upgrade           # Upgrade virtualenv
$ sudo pip  install virtualenvwrapper --upgrade    # Upgrade virtualenvwrapper