title: No module named 'json' after installing simplejson
body: <p>I am working in Ubuntu 14.04 and I have multiple versions of Python on my machine (they include python2.7 and python3.4). Few days back, I installed <code>simplejson</code> on my system. I don't remember how I did that but I guess it must be similar to <code>pip install simplejson</code>. However, now a strange problem has started appearing when I try installing any python package. For example, just now I tried installing <code>Tkinter</code> using <code>sudo pip3.4 install Tkinter</code> and it throws the following error:</p>
  
  <pre><code>Traceback (most recent call last):
    File "/usr/local/bin/pip3.4", line 9, in &lt;module&gt;
      load_entry_point('pip==1.5.4', 'console_scripts', 'pip3.4')()
    File "/usr/lib/python3/dist-packages/pkg_resources.py", line 351, in load_entry_point
      return get_distribution(dist).load_entry_point(group, name)
    File "/usr/lib/python3/dist-packages/pkg_resources.py", line 2363, in load_entry_point
      return ep.load()
    File "/usr/lib/python3/dist-packages/pkg_resources.py", line 2088, in load
      entry = __import__(self.module_name, globals(),globals(), ['__name__'])
    File "/usr/lib/python3/dist-packages/pip/__init__.py", line 61, in &lt;module&gt;
      from pip.vcs import git, mercurial, subversion, bazaar  # noqa
    File "/usr/lib/python3/dist-packages/pip/vcs/subversion.py", line 4, in &lt;module&gt;
      from pip.index import Link
    File "/usr/lib/python3/dist-packages/pip/index.py", line 15, in &lt;module&gt;
      from pip.wheel import Wheel, wheel_ext
    File "/usr/lib/python3/dist-packages/pip/wheel.py", line 25, in &lt;module&gt;
      from distlib.scripts import ScriptMaker
    File "/usr/share/python-wheels/distlib-0.1.8-py2.py3-none-any.whl/distlib/scripts.py", line 15, in &lt;module&gt;
    File "/usr/share/python-wheels/distlib-0.1.8-py2.py3-none-any.whl/distlib/resources.py", line 20, in &lt;module&gt;
    File "/usr/share/python-wheels/distlib-0.1.8-py2.py3-none-any.whl/distlib/util.py", line 11, in &lt;module&gt;
  ImportError: No module named 'json'
  </code></pre>
  
  <p>Sometimes I can fix this if the error tells me that in one of the files I have:</p>
  
  <pre><code>import json
  </code></pre>
  
  <p>which I simply convert to </p>
  
  <pre><code>import simplejson as json
  </code></pre>
  
  <p>I tried uninstalling simplejson:</p>
  
  <pre><code>sudo pip uninstall simplejson
  </code></pre>
  
  <p>but it gives me the same error: json not found. </p>
  
  <p>Can anybody please help me fix this so that I would happily be able to install python packages? Thanks in advance. </p>