Log Message:
Update to 0.58:

0.58    2015-07-21 16:00 UTC
        + Add : If a non-len magic callback returns a reference, it will now
                only be freed at the end of the statement that caused the
                magic to trigger. This allows the user to attach free magic
                (or a plain destructor) to a token returned from the callbacks
                in order to defer an action after the magic is processed by
                perl.
        + Fix : Test failures of threads tests on systems with harsh resource
                constraints causing the threads to exit() during run.