Normally, SSLSocket.recv_into(buffer) returns an integer -- the number of bytes read into buffer. But if buffer is None and the SSL connection is opened (self._sslobj is not None), it is equivalent to SSLSocket.read(1024) -- read up to 1024 bytes and return the read bytes.

It looks weird and I wonder whether there is a use case for this. This behavior was from the start, from 6e027db where this method was added, so I do not see some obvious error that was introduced later.