title: sqlite3.OperationalError: database is locked while import ipdb
body: <p>When I import ipdb, I seen below error message. </p>
  
  <blockquote>
    <p>import ipdb
    Traceback (most recent call last):
      File "/auto/xr_pi/PRODUCTION/pyATS/lib/python3.4/site-packages/ipdb/<strong>main</strong>.py", line 32, in 
        get_ipython
    NameError: name 'get_ipython' is not defined</p>
  </blockquote>
  
  <p>During handling of the above exception, another exception occurred:</p>
  
  <blockquote>
    <p>Traceback (most recent call last):
      File "", line 1, in 
      File "/auto/xr_pi/PRODUCTION/pyATS/lib/python3.4/site-packages/ipdb/<strong>init</strong>.py", line 16, in 
        from ipdb.<strong>main</strong> import set_trace, post_mortem, pm, run, runcall, runeval, launch_ipdb_on_exception
      File "/auto/xr_pi/PRODUCTION/pyATS/lib/python3.4/site-packages/ipdb/<strong>main</strong>.py", line 51, in 
        ipshell = InteractiveShellEmbed()
      File "/auto/xr_pi/PRODUCTION/pyATS/lib/python3.4/site-packages/IPython/terminal/embed.py", line 68, in <strong>init</strong>
        super(InteractiveShellEmbed,self).<strong>init</strong>(**kw)
      File "/auto/xr_pi/PRODUCTION/pyATS/lib/python3.4/site-packages/IPython/core/interactiveshell.py", line 513, in <strong>init</strong>
        self.init_history()
      File "/auto/xr_pi/PRODUCTION/pyATS/lib/python3.4/site-packages/IPython/core/interactiveshell.py", line 1636, in init_history
        self.history_manager = HistoryManager(shell=self, parent=self)
      File "/auto/xr_pi/PRODUCTION/pyATS/lib/python3.4/site-packages/IPython/core/history.py", line 520, in <strong>init</strong>
        self.new_session()
      File "", line 2, in new_session
      File "/auto/xr_pi/PRODUCTION/pyATS/lib/python3.4/site-packages/IPython/core/history.py", line 68, in needs_sqlite
        return f(self, *a, **kw)
      File "/auto/xr_pi/PRODUCTION/pyATS/lib/python3.4/site-packages/IPython/core/history.py", line 538, in new_session
        NULL, "") """, (datetime.datetime.now(),))
    sqlite3.OperationalError: database is locked</p>
  </blockquote>