This patch is a follow up patch fixing some nits left by the review
da9c3b0adc67efa916fc534d975823c0a45948a1, this patch adds the
wwn_with_extension and wwn_vendor_extension root device hints to the
"serializable_fields" list attribute of the BlockDevice class and fixes
some tests.
Change-Id: I6039be535988319276f9ac355c80997d34328ce8