Fix make_deferred_yieldable to work with coroutines

tests/util/test_logcontext.py

@@ -179,6 +179,30 @@ class LoggingContextTestCase(unittest.TestCase):
             nested_context = nested_logging_context(suffix="bar")
             self.assertEqual(nested_context.request, "foo-bar")
 
+    @defer.inlineCallbacks
+    def test_make_deferred_yieldable_with_await(self):
+        # an async function which retuns an incomplete coroutine, but doesn't
+        # follow the synapse rules.
+
+        async def blocking_function():
+            d = defer.Deferred()
+            reactor.callLater(0, d.callback, None)
+            await d
+
+        sentinel_context = LoggingContext.current_context()
+
+        with LoggingContext() as context_one:
+            context_one.request = "one"
+
+            d1 = make_deferred_yieldable(blocking_function())
+            # make sure that the context was reset by make_deferred_yieldable
+            self.assertIs(LoggingContext.current_context(), sentinel_context)
+
+            yield d1
+
+            # now it should be restored
+            self._check_test_key("one")
+
 
 # a function which returns a deferred which has been "called", but
 # which had a function which returned another incomplete deferred on