206 /*The following convoluted conditional determines whether or not
207  *the current connection should remain persistent after this response
208  *(a.k.a. HTTP Keep-Alive) and whether or not the output message
209  *body should use the HTTP/1.1 chunked transfer-coding. In English,
210  *
211  *  IF  we have not marked this connection as errored;
212  *  and the response body has a defined length due to the status code
213  *  being 304 or 204, the request method being HEAD, already
214  *  having defined Content-Length or Transfer-Encoding: chunked, or
215  *  the request version being HTTP/1.1 and thus capable of being set
216  *  as chunked [we know the (r->chunked = 1) side-effect is ugly];
217  *  and the server configuration enables keep-alive;
218  *  and the server configuration has a reasonable inter-request timeout;
219  *  and there is no maximum # requests or the max hasn't been reached;
220  *  and the response status does not require a close;
221  *  and the response generator has not already indicated close;
222  *  and the client did not request non-persistence (Connection: close);
223  *  and we haven't been configured to ignore the buggy twit
224  *  or they're a buggy twit coming through a HTTP/1.1 proxy
225  *  and the client is requesting an HTTP/1.0-style keep-alive
226  *  or the client claims to be HTTP/1.1 compliant (perhaps a proxy);
227  *  THEN we can be persistent, which requires more headers be output.
228  *
229  *Note that the condition evaluation order is extremely important.
230  */