better null str test

Author: Frederick888

tests/null_str.phpt

@@ -10,11 +10,13 @@ $val = "foo\0bar";
 $bdict = new bdict();
 $bdict->set($key, new bstr($val));
 echo strlen($bdict->get($key)->get()) . "\n";
-echo bin2hex($bdict->get($key)->get());
+echo bin2hex($bdict->get($key)->get()) . "\n";
+echo bin2hex($bdict);
 
 exit(0);
 ?>
 --EXPECTF--
 7
 666f6f00626172
+6431313a68656c6c6f00776f726c64373a666f6f0062617265