title: Mongo ObjectID: "can't compare offset-naive and offset-aware datetimes" even with pytz
body: <p>I'm trying to prettify ObjectIDs timestamp with <a href="http://pypi.python.org/pypi/py-pretty">py-pretty</a> but it keeps giving me a TypeError:</p>
  
  <pre><code>TypeError: can't compare offset-naive and offset-aware datetimes
  </code></pre>
  
  <p>even after I attempt convert the timestamp to a timezone unaware UTC date with Pytz. This is the code I'm trying</p>
  
  <pre><code>import datetime
  import pytz
  import pretty
  # ...
  
  song = db.songs.find_one( { 'GUID' : 0123 } )
  dateTimeUnaware = song['_id'].generation_time.now(pytz.utc)
  prettyDate = pretty.date( dateTimeUnaware )
  </code></pre>
  
  <p>Why does this keep giving me the type error? Shouldn't the pytz function make it timezone agnostic?</p>