issue moving from 0.3.0 to v0.4.0
0.4.0 seems to use np.add.reduceat() where 0.3.0 doesn't which is causing issues with some code I run during the evaluation of the beta in a PanelOLS.  In particular, during the evaluation of self._y_trans.count() in _time_obs_count() there is a seg fault.

I'm not familiar with the internals of numpy or pandas but it looks like 0.4.0 passes in a zero length array for the output.  The debugger won't go into the np.add.reduceat() code but it segfaults as soon as I make the next step

python -m pdb valModel1.py
b /usr/local/lib/python2.7/site-packages/pandas/core/series.py:505

> /usr/local/lib/python2.7/site-packages/pandas/core/series.py(505)_count_level()
> -> np.add.reduceat(mask, locs[start:end], out=out)
> (Pdb) np.shape(mask)
> (0,)
> (Pdb) np.shape(locs)
> (271,)
> (Pdb) np.shape(out)
> (0,)

And then seg faults

Its possible this is an underlying numpy issue but everything works fine on the same system with 0.3.0.

If this is of interest to you I can give you more info.

I'm running Freebsd 8.1 with the following packages and pandas compiled from a git pull

python27-2.7.1_1
cython-0.14.1
py27-numpy-1.5.1,1
py27-matplotlib-1.0.1
py27-scipy-0.8.0_1
py27-dateutil-1.5
py27-setuptools-0.6c11_1
py27-nose-1.0.0
py27-pytz-2011c

Best
Dan
