Avoid testing mergeability of a patch when not targeting master, so that
patches tested via other means (e.g. maintainer branches and AB runs)
don't get unnecessarily reviewed an extra time.
(From OE-Core rev: e6cf23e353f48c57249681bd0b12bd8494d4959a)
Signed-off-by: Trevor Gamblin <tgamblin@baylibre.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>