This comparison is interesting even in the case of empty vales. Enabling
this warning actually found a bug in the metadata in avahi. Make the
code handle None specifically and also remove the dead code path in the
second if statement.
(Bitbake rev: a4cd4c56284812efb2a2bc0c8667ddad073f8e94)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>