title: KeyError when trying to unpickle list
body: <p>I have a file containing a pickled list of lists of floats. I can load the list without problems in the same machine that pickled it, but when I tried it in another one, I got the following error:</p>
  
  <pre><code>Traceback (most recent call last):
  File "&lt;console&gt;", line 2, in &lt;module&gt;
  File "/usr/lib/python2.7/pickle.py", line 1378, in load
    return Unpickler(file).load()
  File "/usr/lib/python2.7/pickle.py", line 858, in load
    dispatch[key](self)
  KeyError: '\x00'
  </code></pre>
  
  <p>The two python versions are 2.7.0 (on the original machine) and 2.7.2 (on the one that tried unpickling the file). I don't think there should be any incompatibility just because of that.</p>