Issue #2171315 by sun, Xano, diarmy, tim.plunkett: Ensure a NULL container in UnitTestCase::setUp().
Issue #2204345 by tim.plunkett: Adjust PluginBag's instance handling methods.
Issue #1774104 by sun: Replace all trivial drupal_write_record() calls with db_merge().
Issue #2205799 by cam8001, davidgrayston: PHPUnit should be configured to work consistently on all environments.
Issue #2190665 by alexpott: Remove persist flag from services that do not need it.