You can clone with
HTTPS or Subversion.
in system/core/Common.php line 127~129 says:
// Look for the class first in the native system/libraries folder
// thenin the local application/libraries folder
foreach (array(BASEPATH, APPPATH) as $path)
thus, we can't replace any core classes,
plz fix, thanks!
Fix #8 - Load core classes from the application folder first.