Release v0.16 silently introduced a new option new_fds_for_rpc that supports communication over fds other than stdin&stdout. A few fixes and tweaks around that:
stdout_handlingbuffer_age_ilmit correctlyConnection.create and in Connection.with_close.Writer.splice to transfer stderr/stdoutIn Command_rpc.Connection.create, change how stderr handling is specified:
Propagate_stderr corresponds to old setting ~propagate_stderr:trueIgnore_stderrcorresponds to ~propagate_stderr:falseCustom _ lets the user specify custom handling of stderr