* The returned string belongs to 'thread' and as such, should not be
* modified by the caller and will only be valid for as long as the
* thread is valid, (which is until notmuch_thread_destroy or until
* The returned string belongs to 'thread' and as such, should not be
* modified by the caller and will only be valid for as long as the
* thread is valid, (which is until notmuch_thread_destroy or until