Warn if a test defeats performance optimizations.
Use Queue Memory backend by default.
[FIXME] system_cron() hard-codes database queries on 'queue'.
[debug] ConfigImporter hides errors.
[FIXME] PhpStorageFactory does not support stream wrappers.
Fixed Database tests require multiple connections.
[fixup] Added @todo for APC(u).
Fixed bogus tests.
[FIXME] drupal_rewrite_settings() does not support stream wrappers.
Fixed bogus expectations in ModuleHandlerTest.