We need to set the setscene tasklist before we call into the
taskhash/unihash code else the behaviour is inconsistent.
Avoid reporting hashes for non setscene tasks since we'd never
query that.
(Bitbake rev: 419a7840b8627278db694029c25df00214d01d96)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>