Additional uncaught exception thrown while handling exception.

Original

PDOException: SQLSTATE[HY000] [2005] Unknown MySQL server host 'mysql' (2) in variable_initialize() (line 1189 of /drupal/site/includes/bootstrap.inc).

Additional

PDOException: SQLSTATE[HY000] [2005] Unknown MySQL server host 'mysql' (2) in db_merge() (line 2504 of /drupal/site/includes/database/database.inc).