Fix mx.symbol.numpy._Symbol.__deepcopy__ logic error

python/mxnet/symbol/numpy/_symbol.py

@@ -283,7 +283,7 @@ def __neg__(self):
         return negative(self)
 
     def __deepcopy__(self, _):
-        return super(_Symbol, self).as_np_ndarray()
+        return super().__deepcopy__(_).as_np_ndarray()
 
     def __eq__(self, other):
         """x.__eq__(y) <=> x == y"""

tests/python/unittest/test_symbol.py

@@ -479,3 +479,13 @@ def test_infershape_happens_for_all_ops_in_graph():
 
     assert False
 
+def test_symbol_copy():
+    a = mx.sym.Variable('a')
+    b = copy.copy(a)
+    b._set_attr(name='b')
+    assert a.name == 'a' and b.name == 'b'
+
+    a = mx.sym.numpy._Variable('a')
+    b = copy.copy(a)
+    b._set_attr(name='b')
+    assert a.name == 'a' and b.name == 'b'