asyncio: sync with Tulip

- repr(Task) and repr(CoroWrapper) now also includes where these objects were
  created. If the coroutine is not a generator (don't use "yield from"), use
  the location of the function, not the location of the coro() wrapper.
- Fix create_task(): truncate the traceback to hide the call to create_task().

Lib/asyncio/tasks.py

@@ -101,7 +101,12 @@ class Task(futures.Future):
         else:
             info.append(self._state.lower())
 
-        info.append(coroutines._format_coroutine(self._coro))
+        coro = coroutines._format_coroutine(self._coro)
+        info.append('coro=<%s>' % coro)
+
+        if self._source_traceback:
+            frame = self._source_traceback[-1]
+            info.append('created at %s:%s' % (frame[0], frame[1]))
 
         if self._state == futures._FINISHED:
             info.append(self._format_result())