'Regression test for an issue found in *writing* the regression test for
https://github.com/astropy/astropy/issues/2363, where comparison of
the list of values for a commentary keyword did not always compare
correctly with other iterables.'

def test_commentary_comparison(self):

    header = fits.Header()
    header['HISTORY'] = 'hello    world'
    header['HISTORY'] = 'hello    world'
    header['COMMENT'] = 'hello    world'
    assert (header['HISTORY'] != header['COMMENT'])
    header['COMMENT'] = 'hello    world'
    assert (header['HISTORY'] == header['COMMENT'])
