Make sure that HTTPClient disconnects from the old server if redirecting to new one

Fixes: https://github.com/espressif/arduino-esp32/issues/4763

libraries/HTTPClient/src/HTTPClient.cpp

@@ -269,13 +269,20 @@ bool HTTPClient::beginInternal(String url, const char* expectedProtocol)
 
     // get port
     index = host.indexOf(':');
+    String the_host;
     if(index >= 0) {
-        _host = host.substring(0, index); // hostname
+        the_host = host.substring(0, index); // hostname
         host.remove(0, (index + 1)); // remove hostname + :
         _port = host.toInt(); // get port
     } else {
-        _host = host;
+        the_host = host;
+    }
+    if(_host != the_host && connected()){
+        log_d("switching host from '%s' to '%s'. disconnecting first", _host.c_str(), the_host.c_str());
+        _canReuse = false;
+        disconnect(true);
     }
+    _host = the_host;
     _uri = url;
     log_d("host: %s port: %d url: %s", _host.c_str(), _port, _uri.c_str());
     return true;