server through a proxy and have the remote https server port set using the
  CURLOPT_PORT option, protocol gets reset to http from https after the first
  request.

  User defined URL was modified internally by libcurl and subsequent reuse of
  the easy handle may lead to connection using a different protocol (if not
  originally http).

  I found that libcurl hardcoded the protocol to "http" when it tries to
  regenerate the URL if CURLOPT_PORT is set. I tried to fix the problem as
  follows and it's working fine so far