Avoid adding keyword arguments to with_mask

spectral_cube/spectral_cube.py

@@ -1132,7 +1132,7 @@ def percentile(self, q, axis=None, iterate_rays=False, **kwargs):
 
         return result
 
-    def with_mask(self, mask, inherit_mask=True, wcs_tolerance=None, **kwargs):
+    def with_mask(self, mask, inherit_mask=True, wcs_tolerance=None):
         """
         Return a new SpectralCube instance that contains a composite mask of
         the current SpectralCube and the new ``mask``.  Values of the mask that
@@ -1179,7 +1179,7 @@ def with_mask(self, mask, inherit_mask=True, wcs_tolerance=None, **kwargs):
         new_mask._validate_wcs(new_data=self._data, new_wcs=self._wcs,
                                wcs_tolerance=wcs_tolerance or self._wcs_tolerance)
 
-        return self._new_cube_with(mask=new_mask, wcs_tolerance=wcs_tolerance, **kwargs)
+        return self._new_cube_with(mask=new_mask, wcs_tolerance=wcs_tolerance)
 
     def __getitem__(self, view):
 
@@ -3971,12 +3971,10 @@ def mask_channels(self, goodchannels):
             raise ValueError("goodchannels must have a length equal to the "
                              "cube's spectral dimension.")
 
-        mask = BooleanArrayMask(goodchannels[:,None,None], self._wcs,
-                                shape=self._data.shape)
-
-        return self.with_mask(goodchannels[:,None,None],
-                              goodbeams_mask=np.logical_and(goodchannels, self.goodbeams_mask))
+        cube = self.with_mask(goodchannels[:,None,None])
+        cube.goodbeams_mask = np.logical_and(goodchannels, self.goodbeams_mask)
 
+        return cube
 
     def spectral_interpolate(self, *args, **kwargs):
         raise AttributeError("VaryingResolutionSpectralCubes can't be "