The status can be PGSQL_TRANSACTION_IDLE (currently idle),
PGSQL_TRANSACTION_ACTIVE (a command is in progress),
PGSQL_TRANSACTION_INTRANS (idle, in a valid transaction block),
or PGSQL_TRANSACTION_INERROR (idle, in a failed transaction block).
PGSQL_TRANSACTION_UNKNOWN is reported if the connection is bad.
PGSQL_TRANSACTION_ACTIVE is reported only when a query
has been sent to the server and not yet completed.