PEP-3333: LatinIter.__next__ should call self._next before testing self.transform_ok (#2128)

pep-3333.txt

@@ -424,10 +424,11 @@ a block boundary.)
             return self
 
         def __next__(self):
+            data = self._next()
             if self.transform_ok:
-                return piglatin(self._next())   # call must be byte-safe on Py3
+                return piglatin(data)   # call must be byte-safe on Py3
             else:
-                return self._next()
+                return data
 
     class Latinator: