Define METADATA_BRANCH and METADATA_REVISION using immediate expansion.
This avoids running `git rev-parse HEAD` multiple times during recipe
parsing.
(From OE-Core rev: 34e1841ec14c545c73fbe03a9f946d43d65ab326)
Signed-off-by: Peter Kjellerstedt <peter.kjellerstedt@axis.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>