This fixes a regression introduced in 77d94dd5
("Speed up RuleTool.searchRuleList by quickly filtering out rules"),
causing TestRule.test_09_expandTwoRules to fail.

UNG code contains overrides of default ERP5 UI and KM UI which breaks it so add theme to its default skin selection (same way as KM).

Otherwise other directories may be considered as part of erp5.util
(such as product).