added extra check for shallow copy test
@@ -182,6 +182,7 @@ class TestEOPatch(unittest.TestCase):
eop_copy.mask['CLM'] += 1
assert eop == eop_copy
+ assert eop.mask['CLM'] is eop_copy.mask['CLM']
eop_copy.timestamp.pop()
assert eop != eop_copy
