Add test for entity.role after retrieve

tests/test_misc.py

@@ -581,3 +581,10 @@ def test_cache_performance():
         t2 = t.time() - t1
         print("Time [s]: " + str(t2))
         n += 10
+
+def test_role_after_retrieve():
+    rt = db.RecordType("TestRT").insert()
+    entity = db.Entity(id=rt.id)
+    assert entity.role is None
+    entity.retrieve()
+    assert entity.role == rt.role