unlink(cake_core_file_map) permission denied

[Oliboy50]

Issue

Every time I clear All cache files, it clears everything except *_cake_core_file_map.
I tried to delete this file myself then clear the cache again after it was regenerated... but still the same.
I don't know why this file is different from others.

Full error

Warning (2): unlink(C:\wamp\www\my-application\v5\app\tmp\cache\persistent\my_application_v5_cake_core_file_map): Permission denied [APP\Plugin\ClearCache\Lib\ClearCache.php, line 76]

Current workaround

I clear All cache engines to fully remove all the cached files... it's weird enough but *_cake_core_file_map is also deleted this way.

Version

Cakephp 2.5.4
DebugKit master
ClearCache master