[issue35928] socket makefile read-write discards received data

Palle Ravn added the comment: >>> f = TextIOWrapper(BufferedRWPair(BytesIO(b"Hello\nYou\n"), BytesIO())) >>> f.readline() 'Hello\n' >>> f.write(_) 6 >>> f.readline() # Returns empty string '' -- __

[issue35928] socket makefile read-write discards received data

New submission from Palle Ravn : Using socket.makefile in read-write mode had a bug introduced between version 3.6.6 and 3.6.7. The same bug is present in version 3.7.x. The below code example will behave very differently between 3.6.6 and 3.6.7. It's based on the echo-server example from