pad_spectrum does not fully obey axis argument

[zpace]

The FilterResponse object's pad_spectrum method appears to not add elements along the correct axis. For example...

import numpy as np, astropy.units as u, speclite.filters as filters
# 1-dim wavelength array
lam0 = np.arange(3800., 5500., 1.) * u.AA
# compatible datacube shape
flam0 = np.tile(np.ones_like(lam0.value)[..., None, None], (1, 20, 20)) * \
    u.Unit('1e-17 erg/s/cm2/AA')
sdss = filters.load_filters('sdss2010-*')
flam, lam = sdss.pad_spectrum(spectrum=flam0, wavelength=lam0, method='zero', axis=0)
print(flam0.shape, lam0.shape, flam.shape, lam.shape)

which outputs (1700, 20, 237) (1917,) instead of (1917, 20, 20), (1917,)

my version is 0.5

The workaround seems to be to np.moveaxis from 0 ==> -1 prior to calling pad_spectrum, and then reversing that operation after.