Mesh.copy() is broken

>>> from meshmode.mesh.generation import generate_regular_rect_mesh as grrm
>>> m = grrm()
>>> m.copy()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/matt/src/pytools/pytools/__init__.py", line 156, in copy
    return self.__class__(**self.get_copy_kwargs(**kwargs))
TypeError: __init__() got an unexpected keyword argument 'btag_to_index'