Pandas sum column with scalar results in zeros
I am summing a column of a pandas dataframe with a scalar and the result is a column full of zeros. The weird thing is that sometimes it will return zeros and sometimes it won't.

With this code I get a similar error:

``` python
import pandas as pd
import numpy as np
from pdb import set_trace as pdb

for _ in xrange(100):
    data = np.random.randint(1,100000,1000000)
    df = pd.DataFrame(data,columns=['column'])
    scalar = np.random.randint(1,100000)
    df.column += scalar
    if df.column.max()==0:
        pdb()
```

My `df.column` gets full of zeros every now and then.

Discussion on stackoverflow:
http://stackoverflow.com/questions/35057969/pandas-sum-column-with-scalar-results-in-zeros
