[HttpKernel] fixed a PHP notice

src/Symfony/Component/HttpKernel/Kernel.php

@@ -242,8 +242,11 @@ abstract class Kernel implements KernelInterface
             throw new \RuntimeException(sprintf('File name "%s" contains invalid characters (..).', $name));
         }
 
-        $name = substr($name, 1);
-        list($bundleName, $path) = explode('/', $name, 2);
+        $bundleName = substr($name, 1);
+        $path = '';
+        if (false !== strpos($bundleName, '/')) {
+            list($bundleName, $path) = explode('/', $bundleName, 2);
+        }
 
         $isResource = 0 === strpos($path, 'Resources') && null !== $dir;
         $overridePath = substr($path, 9);
@@ -280,7 +283,7 @@ abstract class Kernel implements KernelInterface
             return $first && $isResource ? $files[0] : $files;
         }
 
-        throw new \InvalidArgumentException(sprintf('Unable to find file "@%s".', $name));
+        throw new \InvalidArgumentException(sprintf('Unable to find file "%s".', $name));
     }
 
     /**