I think this is a very important request cause it can be the case, that the PB command is not able to determine the end of a StdErr line if the sender application does not terminate a line. (FFMPEG for ex)
In this case, your application will stop working until the sending application sends a terminating character. (I think this is the was this command works, pls correct me if I'm wrong).
This can also be a security issue for your own application.