- We no longer support setting the CURLOPT_URL option from inside a callback

such as the CURLOPT_SSL_CTX_FUNCTION one treat that as if it was a Location:
  following. The patch that introduced this feature was done for 7.11.0, but
  this code and functionality has been broken since about 7.15.4 (March 2006)
  with the introduction of non-blocking OpenSSL "connects".

  It was a hack to begin with and since it doesn't work and hasn't worked
  correctly for a long time and nobody has even noticed, I consider it a very
  suitable subject for plain removal. And so it was done.

lib/urldata.h

@@ -1250,10 +1250,6 @@ struct UrlState {
 struct DynamicStatic {
   char *url;        /* work URL, copied from UserDefined */
   bool url_alloc;   /* URL string is malloc()'ed */
-  bool url_changed; /* set on CURL_OPT_URL, used to detect if the URL was
-                       changed after the connect phase, as we allow callback
-                       to change it and if so, we reconnect to use the new
-                       URL instead */
   char *referer;    /* referer string */
   bool referer_alloc; /* referer sting is malloc()ed */
   struct curl_slist *cookielist; /* list of cookie files set by