[task] fix return statement missing stan errors

Author: connorhu

Diff for: lib/task/test/sfTestFunctionalTask.class.php

@@ -108,5 +108,7 @@ protected function execute($arguments = [], $options = [])
 
             return $ret;
         }
+
+        return 0;
     }
 }

Diff for: lib/task/test/sfTestPluginTask.class.php

@@ -67,6 +67,6 @@ protected function execute($arguments = [], $options = [])
         $finder = sfFinder::type('file')->follow_link()->name('*Test.php');
         $h->register($finder->in($h->base_dir));
 
-        return $h->run();
+        return $h->run() ? 0 : 1;
     }
 }

Diff for: lib/task/test/sfTestUnitTask.class.php

@@ -102,5 +102,7 @@ protected function execute($arguments = [], $options = [])
 
             return $ret;
         }
+
+        return 0;
     }
 }