'Remove the ``item`` in an evolver of the ``original`` ``PSet``, and if
the item is an uncommitted ``_EvolverProxy`` remove it from the list of
children so that the item is not persisted when the structure is
finally committed.
:param item: The object to be removed from the wrapped ``PSet``
:returns: ``self``'

def remove(self, item):

    self._children.pop(item, None)
    try:
        self._evolver.remove(item)
    except KeyError:
        pass
    return self
