merge 0.19.x branch into master

tests/run/yield_from_pep380.pyx

@@ -9,10 +9,17 @@ see <http://www.cosc.canterbury.ac.nz/greg.ewing/python/yield-from/YieldFrom-Pyt
 
 import sys
 
+try:
+    _next = next  # not in Py<=2.5
+except NameError:
+    def _next(it):
+        return it.next()
+
 def _lines(trace):
     for line in trace:
         print(line)
 
+
 def test_delegation_of_initial_next_to_subgenerator():
     """
     >>> _lines(test_delegation_of_initial_next_to_subgenerator())
@@ -1006,8 +1013,6 @@ def test_delegating_generators_claim_to_be_running_close():
     return ret
 
 
-_next = next  # keep it around for Py<=2.5
-
 def yield_in_return(x):
     """
     >>> x = yield_in_return(range(3))