Upgraded 2.0.3 to 2.1.0 cannot extend Loader.php anmyore

[eluser]rparavicini[/eluser]
As the title says, I upgraded my installation from 2.0.3 to 2.1.0 and my extended MY_Loader.php is disregarded.
Everything worked fine in 2.0.3 and below, but in 2.1.0 my file is not used anymore by CI. I have changed the autoloader class so that helpers and languages are loaded after libraries (so I can use Session and Database in helpers and languages) and it stopped working in 2.1.0.

What I found out today, if I completely replace the Loader.php with a custom one (copy of original with the changes i extended in 2.0.3) it worked again, so my presumption is:

Extending Loader.php is not working, completely modifying and replacing it is possible.

Anybody has the same problems, or is it just me?

P.S.: I have not replaced my Loader.php in the systems folder, but copied it to the application/core folder and made the changes i needed.