Bug 2038: Compatibility with Google Cloud S3 API when duplicating files

https://winscp.net/tracker/2038
(cherry picked from commit f5eee02e274744dcb5326136eefff827e437eb5f)

Source commit: 87b4e426dc85c8a87a7569e0dd1f55e4cb7d5e5d

libs/libs3/src/request.c

@@ -1233,6 +1233,11 @@ static S3Status setup_neon(Request *request,
     {
         ne_set_request_body_provider(request->NeonRequest, (ne_off_t)params->toS3CallbackTotalSize, neon_read_func, request);
     }
+    else if (params->httpRequestType == HttpRequestTypeCOPY)
+    {
+        // Google cloud needs "Content-Length: 0" header
+        ne_set_request_body_buffer(request->NeonRequest, "", 0);
+    }
 
     // WINSCP (Last-Modified parsed in response_headers_handler_done)