Autoloader is quiet if another one is registered.

Do not throw an exception in the autoloader if another one is
registered, except if it is used through the from/import classic call
(without requiring the load the file).
[auto] Merge from Core

    • #79693c7 — Autoloader is quiet if another one is registered. (Ivan Enderlin, 2013-08-23)

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Merge remote branch 'library-core/master'