Message 252453 - Python tracker

I would avoid suggesting one can return non-byte-strings; treat that as an implementation detail. Maybe something like:

The functions *master_read* and *stdin_read* are passed a file descriptor which they should read from, and should return a byte string. The defaults try to read 1024 bytes each time they are called. Returning an empty string is be interpreted as an EOF condition, and the *_read* function will no longer be called.