curl: curl reuses an HTTPS connection when a response is already buffered in the TLS stack

curl master 15292ed75, 8.23.1-DEV reuses an idle HTTP/1.1-over-TLS connection even when a complete extra response is already buffered in OpenSSL/GnuTLS. The ef6b17cf1 fix only polls the socket: Curlcpoolconnseemshealthy lib/conncache.c:1073, called from lib/url.c:1071 uses Curlconnisalive, and...