Fix issue where GCM pushkins behind proxy fail to start

Author: devonh

sygnal/sygnal.py

@@ -14,6 +14,7 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+import asyncio
 import copy
 import importlib
 import logging
@@ -28,7 +29,7 @@
 from opentracing import Tracer
 from opentracing.scope_managers.asyncio import AsyncioScopeManager
 from twisted.internet import asyncioreactor, defer
-from twisted.internet.defer import Deferred, ensureDeferred
+from twisted.internet.defer import Deferred
 from twisted.internet.interfaces import (
     IReactorCore,
     IReactorFDSet,
@@ -225,7 +226,9 @@ def run(self) -> None:
         @defer.inlineCallbacks
         def start() -> Generator[Deferred[Any], Any, Any]:
             try:
-                yield ensureDeferred(self.make_pushkins_then_start())
+                yield Deferred.fromFuture(
+                    asyncio.ensure_future(self.make_pushkins_then_start())
+                )
             except Exception:
                 # Print the exception and bail out.
                 print("Error during startup:", file=sys.stderr)