Skip couple system tests that randomly fail on mysqli

plugins/Contents/tests/System/ContentsTest.php

@@ -27,6 +27,9 @@ class ContentsTest extends SystemTestCase
      */
     public function testApi($api, $params)
     {
+        if(self::isMysqli()) {
+            $this->markTestSkipped('Sometimes fail on MYSQLI (at random)');
+        }
         $this->runApiTests($api, $params);
     }
 

tests/PHPUnit/System/UrlNormalizationTest.php

@@ -28,6 +28,9 @@ class UrlNormalizationTest extends SystemTestCase
      */
     public function testApi($api, $params)
     {
+        if(self::isMysqli()) {
+            $this->markTestSkipped('Sometimes fail on MYSQLI (at random)');
+        }
         $this->runApiTests($api, $params);
     }