print exception when importing pandas.lib
I was trying to install pandas and kept getting the error:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Library/Python/2.7/site-packages/pandas/**init**.py", line 16, in <module>
    raise ImportError('C extensions not built: if you installed already '
ImportError: C extensions not built: if you installed already verify that you are not importing from the source directory

I couldn't figure out what was happening until I made this change and saw from the printed out exception that I  didn't have the dateutils package installed.
