Issue with masked arrays and boolean columns

[astrofrog]

A masked Numpy array with boolean values has by default a fill value of True which causes issues when writing out to e.g. FITS files because the TNULL keyword is set to True, and the next time the table is read in, all True values are masked.

In [3]:ma.array([True,False,True],fill_value=None,mask=None)
Out[3]: 
masked_array(data = [True False True],
             mask = [False False False],
       fill_value = True)