/rooms/{roomId}/event/{eventId} gives 404 on failure but SyTest expects 403

[Cnly]

From https://matrix.org/docs/spec/client_server/r0.5.0#get-matrix-client-r0-rooms-roomid-event-eventid:

Status code 404:

The event was not found or you do not have permission to read this event.

But SyTest:

sytest/tests/30rooms/51event.pl

Line 66 in 19abb60

})->main::expect_http_403;

and

sytest/tests/30rooms/51event.pl

Line 106 in 19abb60

})->main::expect_http_403->then( sub {

[anoadragon453]

Fixed by #667 matrix-org/synapse#5798