adapt test to changes in CPython 3.4+

tests/run/yield_inside_lambda.py

 # mode: run
 # tag: generators, lambda
 
-try:
-    from builtins import next # Py3k
-except ImportError:
-    def next(it):
-        return it.next()
 
 def test_inside_lambda():
     """
@@ -14,8 +9,7 @@ def test_inside_lambda():
     1
     >>> next(obj)
     2
-    >>> next(obj)
-    Traceback (most recent call last):
-    StopIteration
+    >>> try: next(obj)
+    ... except StopIteration: pass
     """
     return lambda:((yield 1), (yield 2))