WiFiClientSecure gets stuck, when send buffers get full #2494
Description
When we send too fast (faster then the TLS connection allows), eventually the send buffers will fill up and write() returns 0 (indicating, that nothing could be written). Normally this means we just retry until all data is sent, but in this case the TLS socket never recovers from this condition (buffers stay full). The only thing we can do is close the socket and go home.