title: Get IPython tab completion for ipdb
body: <p>I have <code>IPython(0.13.1)</code> and <code>ipdb(0.7)</code> installed, I inserted the line <code>import ipdb;ipdb.set_trace()</code> in my script and ran <code>python my_script.py</code>. Now I am in the ipdb prompt and there is some autocompletion (e.g. a bare tab) but it's not the same as the autocompletion I get when I enter IPython. In the ipdb prompt <code>requests.</code> then <code>&lt;tab&gt;</code> (after import) does not give me a list of attributes as in IPython. How do I get that same tab completion as in IPython with ipdb?</p>
  
  <p>Btw, when I run <code>python -m ipdb my_script.py</code> the tab completion works just as in IPython but the downside of this is that it starts the debugger from the first line instead of the line I've put <code>import ipdb;ipdb.set_trace()</code>.</p>