<!-- Please describe the issue in detail here, and fill in the fields below --> ### Reproducing code example: The following code sample passes, but is expected to fail: ```python from numpy.testing import assert_array_almost_equal assert_array_almost_equal(np.array([10, 20]), np.ma.array([10, np.nan], mask=[False, True]), 2) ``` ### Numpy/Python version information: python 3.7.3 numpy 1.17.2