Re-add global and persistent cache groups in WP_UnitTestCase::flush_cache(). Some cache tests mess with global groups and don't restore them. This causes many multisite cache tests to fail when the full test suite is run as groups such as blog-details are not properly global.


git-svn-id: https://unit-tests.svn.wordpress.org/trunk@1332 4a5a2adb-35eb-4268-9a1b-fe04a4134342