diff -r a13d9656f954 Lib/test/test_generators.py
--- a/Lib/test/test_generators.py	Sun Nov 08 11:09:13 2015 +0000
+++ b/Lib/test/test_generators.py	Thu Nov 12 19:15:12 2015 -0500
@@ -260,6 +260,89 @@
             # hence no warning.
             next(g)
 
+    def test_nested_try_1(self):
+        class MainError(Exception):
+            pass
+
+        class SubError(Exception):
+            pass
+
+        def main():
+            try:
+                raise MainError()
+            except MainError:
+                try:
+                    yield
+                except SubError:
+                    pass
+                raise
+
+        coro = main()
+        coro.send(None)
+        try:
+            coro.throw(SubError())
+        except MainError as ex:
+            self.assertIsNone(ex.__cause__)
+            self.assertIsNone(ex.__context__)
+        except Exception as ex:
+            self.fail('MainError expected; got {!r}'.format(ex))
+        else:
+            self.fail('MainError expected; got no exception')
+
+    def test_nested_try_2(self):
+        class MainError(Exception):
+            pass
+
+        class SubError(Exception):
+            pass
+
+        def main():
+            try:
+                raise MainError()
+            except MainError:
+                yield
+
+        coro = main()
+        coro.send(None)
+        try:
+            coro.throw(SubError())
+        except SubError as ex:
+            self.assertIsNone(ex.__cause__)
+            self.assertIs(type(ex.__context__), MainError)
+        except Exception as ex:
+            self.fail('SubError expected; got {!r}'.format(ex))
+        else:
+            self.fail('SubError expected; got no exception')
+
+    def test_nested_try_3(self):
+        class MainError(Exception):
+            pass
+
+        class SubError(Exception):
+            pass
+
+        def main():
+            try:
+                raise MainError()
+            except MainError as ex:
+                try:
+                    yield
+                except SubError:
+                    pass
+                raise ex
+
+        coro = main()
+        coro.send(None)
+        try:
+            coro.throw(SubError())
+        except MainError as ex:
+            self.assertIsNone(ex.__cause__)
+            self.assertIsNone(ex.__context__)
+        except Exception as ex:
+            self.fail('MainError expected; got {!r}'.format(ex))
+        else:
+            self.fail('MainError expected; got no exception')
+
 
 class YieldFromTests(unittest.TestCase):
     def test_generator_gi_yieldfrom(self):
diff -r a13d9656f954 Python/ceval.c
--- a/Python/ceval.c	Sun Nov 08 11:09:13 2015 +0000
+++ b/Python/ceval.c	Thu Nov 12 19:15:12 2015 -0500
@@ -1192,7 +1192,10 @@
     f->f_executing = 1;
 
     if (co->co_flags & (CO_GENERATOR | CO_COROUTINE)) {
-        if (!throwflag && f->f_exc_type != NULL && f->f_exc_type != Py_None) {
+        if ((!throwflag || tstate->exc_type == NULL ||
+                tstate->exc_type == Py_None)
+            && (f->f_exc_type != NULL && f->f_exc_type != Py_None))
+        {
             /* We were in an except handler when we left,
                restore the exception state which was put aside
                (see YIELD_VALUE). */