Set Is Private as per file attribute (#4964)

frappe/public/js/frappe/form/footer/attachments.js

@@ -237,6 +237,7 @@ frappe.ui.get_upload_dialog = function(opts){
 							dialog.$wrapper.find('[name="file_url"]').val(r.message.file_url);
 							dialog.$wrapper.find('.private-file input').prop('checked', r.message.is_private);
 							opts.args.filename = r.message.file_name;
+							opts.args.is_private = r.message.is_private;
 						}
 					});
 				}