From f77d887d81366c1f4405a9644272efb2ee1aa42a Mon Sep 17 00:00:00 2001
From: INADA Naoki <songofacandy@gmail.com>
Date: Thu, 13 Apr 2017 10:35:10 +0900
Subject: [PATCH 1/3] add test

---
 Lib/test/test_asyncio/test_tasks.py | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/Lib/test/test_asyncio/test_tasks.py b/Lib/test/test_asyncio/test_tasks.py
index 754a67519ba9d5b..988b2885c30cd93 100644
--- a/Lib/test/test_asyncio/test_tasks.py
+++ b/Lib/test/test_asyncio/test_tasks.py
@@ -587,6 +587,24 @@ def task():
         self.assertFalse(t._must_cancel)  # White-box test.
         self.assertFalse(t.cancel())
 
+    def test_cancel_at_end(self):
+        """coroutine end right after task is cancelled"""
+        loop = asyncio.new_event_loop()
+        self.set_event_loop(loop)
+
+        @asyncio.coroutine
+        def task():
+            t.cancel()
+            self.assertTrue(t._must_cancel)  # White-box test.
+            return 12
+
+        t = self.new_task(loop, task())
+        self.assertRaises(
+            asyncio.CancelledError, loop.run_until_complete, t)
+        self.assertTrue(t.done())
+        self.assertFalse(t._must_cancel)  # White-box test.
+        self.assertFalse(t.cancel())
+
     def test_stop_while_run_in_complete(self):
 
         def gen():

From 1cc94c94c58f61cf93f404cfbaf06028e1c65865 Mon Sep 17 00:00:00 2001
From: INADA Naoki <songofacandy@gmail.com>
Date: Thu, 13 Apr 2017 10:18:45 +0900
Subject: [PATCH 2/3] bpo-30048: asyncio: fix Task.cancel() was ignored.

example:

    async def coro():
        asyncio.Task.current_task().cancel()
        return 42
    ...
    res = await coro()  # should raise CancelledError
---
 Lib/asyncio/tasks.py     |  7 ++++++-
 Modules/_asynciomodule.c | 12 ++++++++++++
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/Lib/asyncio/tasks.py b/Lib/asyncio/tasks.py
index 4d79367d5cb600e..24238899aae7ca0 100644
--- a/Lib/asyncio/tasks.py
+++ b/Lib/asyncio/tasks.py
@@ -180,7 +180,12 @@ def _step(self, exc=None):
             else:
                 result = coro.throw(exc)
         except StopIteration as exc:
-            self.set_result(exc.value)
+            if self._must_cancel:
+                # Task is cancelled right before coro stops.
+                self._must_cancel = False
+                self.set_exception(futures.CancelledError())
+            else:
+                self.set_result(exc.value)
         except futures.CancelledError:
             super().cancel()  # I.e., Future.cancel(self).
         except Exception as exc:
diff --git a/Modules/_asynciomodule.c b/Modules/_asynciomodule.c
index e902c041e50587e..150ca198d27cfcd 100644
--- a/Modules/_asynciomodule.c
+++ b/Modules/_asynciomodule.c
@@ -1985,6 +1985,16 @@ task_step_impl(TaskObj *task, PyObject *exc)
         if (_PyGen_FetchStopIterationValue(&o) == 0) {
             /* The error is StopIteration and that means that
                the underlying coroutine has resolved */
+            if (task->task_must_cancel) {
+                // Task is cancelled right before coro stops.
+                Py_DECREF(o);
+                task->task_must_cancel = 0;
+                et = asyncio_CancelledError;
+                Py_INCREF(et);
+                ev = NULL;
+                tb = NULL;
+                goto set_exception;
+            }
             PyObject *res = future_set_result((FutureObj*)task, o);
             Py_DECREF(o);
             if (res == NULL) {
@@ -2002,6 +2012,8 @@ task_step_impl(TaskObj *task, PyObject *exc)
 
         /* Some other exception; pop it and call Task.set_exception() */
         PyErr_Fetch(&et, &ev, &tb);
+
+set_exception:
         assert(et);
         if (!ev || !PyObject_TypeCheck(ev, (PyTypeObject *) et)) {
             PyErr_NormalizeException(&et, &ev, &tb);

From 0af81434cd8ea2c9b05369e07ae704191fbc3cfa Mon Sep 17 00:00:00 2001
From: INADA Naoki <songofacandy@gmail.com>
Date: Thu, 11 May 2017 20:51:22 +0900
Subject: [PATCH 3/3] Add news entry

---
 Misc/NEWS | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/Misc/NEWS b/Misc/NEWS
index b6f8c7094c9ef5d..60740bae4ac5f14 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -306,6 +306,10 @@ Extension Modules
 
 Library
 -------
+
+- bpo-30048: Fixed ``Task.cancel()`` can be ignored when the task is
+  running coroutine and the coroutine returned without any more ``await``.
+
 - bpo-29692: Fixed arbitrary unchaining of RuntimeError exceptions in 
   contextlib.contextmanager.
   Patch by Siddharth Velankar.