ISPN-2932 Verify that preloading a read only index in a cache will never...

... hit the cacheloader

https://issues.jboss.org/browse/ISPN-2932



right, especially windows, but not only: even on Linux if we have buffers open, you wouldn't hit a FileNotFoundException.

And in some cases exceptions get swallowed, making it possible for a system to try access filesystem, then fail, and then still succeed in loading it from a network peer.