In T134207#2258850, @hashar wrote:1) CommonFunctionsTest::test_processWikitext_empty preg_replace(): The /e modifier is deprecated, use preg_replace_callback instead 2) CommonFunctionsTest::test_processWikitext_makelinks_form_1 preg_replace(): The /e modifier is deprecated, use preg_replace_callback instead 3) CommonFunctionsTest::test_processWikitext_makelinks_form_2 preg_replace(): The /e modifier is deprecated, use preg_replace_callback instead api/includes/CommonFunctions.php:26 api/tests/CommonFunctionsTest.php:53[...] the regex modifier /e (which eval code) is definitely evil and I can see why it never got supported by HHVM.
Find this pattern where it occurs in the api and replace it with preg_replace_callback