If both VAR and VAR_foo are in subd, we need to ensure VAR_foo gets
returned. Currently the code would work randomly. The only current
user is the rpm packaging backend.
(From OE-Core rev: ad098e40e8c57727892819e131bf18308bf244d2)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>