The dependencies of OVERRIDES were not including DEFAULTTUNE in OE-Core.
This is pulled in by a bb.utils.contains() reference which the override
dependency tracking code wasn't accounting for.
This patch ensures we do track contains references too.
(Bitbake rev: f3ee534cb0560dbb5f88a0ffe01e9305bae102e1)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>