@TimothyBJacobs @spacedmonkey this is an initial commit for https://core.trac.wordpress.org/ticket/43439. It seems to be solving reported issue however, I am concerned about the fact that it's using \WP_REST_Server::match_request_to_handler that is modifying the state of passed request object, and the same method is called later via dispatch method. Is it our concern that it's called second time? Do you have any other ideas to address this issue?