Fixed Python unit test breakage.

Test was testing for a field to be None, even though it is populated
in one particular instance.

Change-Id: Id19848d01498d4c0a684efdb2bf49ff12c5b6758
Tested: on Linux.

tests/py_test.py

@@ -152,8 +152,6 @@ def CheckReadBuffer(buf, offset):
     asserter(monster.Testarrayofstring(0) == b"test1")
     asserter(monster.Testarrayofstring(1) == b"test2")
 
-    asserter(monster.Enemy() is None)
-
     asserter(monster.TestarrayoftablesLength() == 0)
     asserter(monster.TestnestedflatbufferLength() == 0)
     asserter(monster.Testempty() is None)