HTTP/2 request with invalid host name does not end in HostNotFound error

The code that handles host lookup errors skips HTTP/2 connection type (only handles SPDY) and then instead of correct QNetworkReply::error signal we have a rather cryptic message:

QHttpNetworkConnectionPrivate::_q_hostLookupFinished could not de-queue request

which is not helping at all. For 5.9 both http/https schemes will fail the same way, for 5.10 http will fail as expected with HostNotFoundError, since we start as HTTP/1.1.