title: Pip default behavior conflicts with virtualenv?
body: <p>I was following <a href="http://blog.miguelgrinberg.com/post/the-flask-mega-tutorial-part-i-hello-world/page/5" rel="nofollow noreferrer">this tutorial</a></p>
  <p>When I got to <code>virtualenv flask</code> command, I received this error message:</p>
  <pre class="lang-none prettyprint-override"><code>Can not perform a '--user' install. User site-packages are not visible in this virtualenv.
  </code></pre>
  <p>This makes sense as the point of virtualenv is to create a new environment which you can control, and the <code>--user</code> command places everything in a specific location, defeating the objective of separation of dev environment.</p>
  <p>It seems like pip defaults to <code>--user</code> installations though, can I change this default behavior? And, even better, can I get pip to play nice with virtualenv at all times?</p>
  <p>To clarify, here is what my terminal looks like.</p>
  <pre class="lang-none prettyprint-override"><code>MELCHIOR:miguelgrinberg-microblog megablanc$ virtualenv flask
  New python executable in flask/bin/python
  Installing setuptools, pip, wheel...
    Complete output from command /Users/megablanc/Dev...log/flask/bin/python -c &quot;import sys, pip; sys...d\&quot;] + sys.argv[1:]))&quot; setuptools pip wheel:
    Can not perform a '--user' install. User site-packages are not visible in this virtualenv.
  ----------------------------------------
  ...Installing setuptools, pip, wheel...done.
  Traceback (most recent call last):
    File &quot;/Users/megablanc/Library/Python/2.7/bin/virtualenv&quot;, line 11, in &lt;module&gt;
      sys.exit(main())
    File &quot;/Users/megablanc/Library/Python/2.7/lib/python/site-packages/virtualenv.py&quot;, line 832, in main
      symlink=options.symlink)
    File &quot;/Users/megablanc/Library/Python/2.7/lib/python/site-packages/virtualenv.py&quot;, line 1004, in create_environment
      install_wheel(to_install, py_executable, search_dirs)
    File &quot;/Users/megablanc/Library/Python/2.7/lib/python/site-packages/virtualenv.py&quot;, line 969, in install_wheel
      'PIP_NO_INDEX': '1'
    File &quot;/Users/megablanc/Library/Python/2.7/lib/python/site-packages/virtualenv.py&quot;, line 910, in call_subprocess
      % (cmd_desc, proc.returncode))
  OSError: Command /Users/megablanc/Dev...log/flask/bin/python -c &quot;import sys, pip; sys...d\&quot;] + sys.argv[1:]))&quot; setuptools pip wheel failed with error code 1
  </code></pre>