Why won't start_transaction set the transaction isolation level?
Question: The [start_transaction](https://dev.mysql.com/doc/connector-
python/en/connector-python-api-mysqlconnection-start-transaction.html) method
of the MySQLConnection class of `mysql-connector-python` doesn't seem to work
as expected.

    
    
    >>> from mysql.connector import connect
    >>> conn = connect(user = 'john', unix_socket = '/tmp/mysql.sock', database='db7')
    >>> cur = conn.cursor()
    >>> cur.execute("select @@session.tx_isolation")
    >>> cur.fetchone()
    ('REPEATABLE-READ',)
    >>> cur.close()
    True
    >>> conn.start_transaction(isolation_level = 'SERIALIZABLE')
    >>> cur = conn.cursor()
    >>> cur.execute("select @@session.tx_isolation")
    >>> cur.fetchone()
    ('REPEATABLE-READ',)
    

The isolation level remains REPEATABLE-READ despite setting the isolation
level to 'SERIALIZABLE' in the `start_transaction` call. Am I missing
something?


Answer: 
    SELECT TRX_ISOLATION_LEVEL
      FROM information_schema.innodb_trx
     WHERE TRX_MYSQL_THREAD_ID = CONNECTION_ID();
    

This should give you your current transaction's isolation level. However,
unless you `START TRANSACTION WITH CONSISTENT SNAPSHOT;` the transaction won't
likely appear here until after InnoDB has seen you run at least one query.

