SSEClient::wait_for_reconnect() sleeps in 100ms steps until the
reconnect interval has elapsed. With an interval of 0 (for example
"retry: 0" from the server, or set_reconnect_interval(0)) it never
slept at all, so a server that sends "retry: 0" and closes the stream
made the client reconnect in a tight loop. set_max_reconnect_attempts()
does not stop this either, because each successful connection resets
the attempt counter.
Always wait at least one step (100ms). Intervals of 1-99ms already
waited 100ms because of the step size, so only 0 and negative values
change behavior.
yhirose