Dropped column when reading calib constants

[kbruegge]

Hello,

in the function read_calib_constants in dragonboard.calibration the 'chisq_ndf' columns is being dropped. I'm not sure why though.

def read_calib_constants(filepath):
    return pd.read_hdf(filepath).drop('chisq_ndf', axis=1).set_index(
        ['pixel', 'channel', 'cell']
    ).sort_index()

The script plot_all_fit_results.py relies on that column being there.