Bug introduced in:
commit 7bb1807c
Author: Anton Khirnov <anton@khirnov.net>
Date:   Tue Aug 23 12:58:49 2011 +0200

    AVOptions: refactor set_number/write_number

    write_number() does the actual writing of the supplied
    number to destination. Move finding the option and choosing destination
    address out of it.