basil.TL.TransferLayer.Serial.query() doesn't handle receive buffer with old data properly

[laborleben]

Sometimes the receive buffer has data from commands that were previously sent. When issuing a query, query() sends the query command and reads the data from the previous command, because _readline() just checks if read termination occurs at the end of the string (while reading character by character). _readline() does not check if more data is remaining in the receive buffer and if the termination strings exists more than once in the received data.