This ensures that _append, _prepend, overrides, etc are functional when used
on sstate variables (e.g. SSTATE_DIR).
[YOCTO #7564]
(Bitbake rev: 0a9eaa570fdf3862ef26ee537fc74f3be75fd554)
Signed-off-by: Christopher Larson <kergoth@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>