title: Virtualenv OSError - setuptools pip wheel failed with error code 1
body: <p>I get the following error message when trying to set up a virtual environment with virtualenv 15.0.2 but receive OSError setuptools pip wheel failed with error code 1. </p>
  
  <pre><code>New python executable in /Users/nathmorissette/projects/tutorial/venv/bin/python
  Installing setuptools, pip, wheel...
    Complete output from command /Users/nathmorissett...rial/venv/bin/python - setuptools pip wheel:
    Traceback (most recent call last):
    File "&lt;stdin&gt;", line 4, in &lt;module&gt;
    File "/Users/nathmorissette/miniconda2/lib/python2.7/tempfile.py", line 32, in &lt;module&gt;
      import io as _io
    File "/Users/nathmorissette/miniconda2/lib/python2.7/io.py", line 51, in &lt;module&gt;
      import _io
  ImportError: dlopen(/Users/nathmorissette/projects/tutorial/venv/lib/python2.7/lib-dynload/_io.so, 2): Symbol not found: __PyCodecInfo_GetIncrementalDecoder
    Referenced from: /Users/nathmorissette/projects/tutorial/venv/lib/python2.7/lib-dynload/_io.so
    Expected in: dynamic lookup
  
  ----------------------------------------
  ...Installing setuptools, pip, wheel...done.
  Traceback (most recent call last):
    File "/Users/nathmorissette/miniconda2/bin/virtualenv", line 9, in &lt;module&gt;
      load_entry_point('virtualenv==15.0.2', 'console_scripts', 'virtualenv')()
    File "/Users/nathmorissette/miniconda2/lib/python2.7/site-packages/virtualenv-15.0.2-py2.7.egg/virtualenv.py", line 711, in main
      symlink=options.symlink)
    File "/Users/nathmorissette/miniconda2/lib/python2.7/site-packages/virtualenv-15.0.2-py2.7.egg/virtualenv.py", line 944, in create_environment
      download=download,
    File "/Users/nathmorissette/miniconda2/lib/python2.7/site-packages/virtualenv-15.0.2-py2.7.egg/virtualenv.py", line 900, in install_wheel
      call_subprocess(cmd, show_stdout=False, extra_env=env, stdin=SCRIPT)
    File "/Users/nathmorissette/miniconda2/lib/python2.7/site-packages/virtualenv-15.0.2-py2.7.egg/virtualenv.py", line 795, in call_subprocess
      % (cmd_desc, proc.returncode))
  OSError: Command /Users/nathmorissett...rial/venv/bin/python - setuptools pip wheel failed with error code 1
  </code></pre>
  
  <p>Any ideas how to resolve this issue?</p>