First level repair for cx_Oracle 6.0 test regressions
Fixed more regressions caused by cx_Oracle 6.0; at the moment, the only
behavioral change for users is disconnect detection now detects for
cx_Oracle.DatabaseError in addition to cx_Oracle.InterfaceError, as
this behavior seems to have changed. Other issues regarding numeric
precision and uncloseable connections are pending with the upstream
cx_Oracle issue tracker.