The httpOutbound.dial() method incorrectly sets tls.Config.ServerName
to o.Addr, which is the "host:port" address string. TLS SNI must be a
pure hostname without a port number. Sending "host:port" as SNI causes
invalid TLS ClientHello messages and may prevent the proxy server from
correctly routing the connection.
Use o.ServerName instead, which is already correctly set to u.Hostname()
in NewHTTPOutbound.
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