A pair of tiny cleanups in the federation request code. (#8401)

changelog.d/8401.misc

@@ -0,0 +1 @@
+A pair of tiny cleanups in the federation request code.

synapse/handlers/federation.py

@@ -281,7 +281,7 @@ class FederationHandler(BaseHandler):
                             raise Exception(
                                 "Error fetching missing prev_events for %s: %s"
                                 % (event_id, e)
-                            )
+                            ) from e
 
                         # Update the set of things we've seen after trying to
                         # fetch the missing stuff

synapse/http/matrixfederationclient.py

@@ -473,8 +473,6 @@ class MatrixFederationHttpClient:
                             )
 
                             response = await request_deferred
-                    except TimeoutError as e:
-                        raise RequestSendFailed(e, can_retry=True) from e
                     except DNSLookupError as e:
                         raise RequestSendFailed(e, can_retry=retry_on_dns_fail) from e
                     except Exception as e: