adding an XFAIL, as we have an open bug for this test

ext/date/tests/bug51994.phpt

@@ -1,5 +1,7 @@
 --TEST--
 Bug #51994 (date_parse_from_format is parsing invalid date using 'yz' format)
+--XFAIL--
+Bug #51994 isn't fixed yet
 --FILE--
 <?php
 $trans_date = '10153'; // 152nd day of year 2010 -> 03.06.2010
@@ -35,4 +37,4 @@ array(12) {
   }
   ["is_localtime"]=>
   bool(false)
-}
+}