devtool: fix upstream version check for devtool-test-local recipe

(From OE-Core rev: d3ce46246fbb40153f6aa7c07898eb449ef3b0f0)

Signed-off-by: Alexander Kanavin <alexander.kanavin@linux.intel.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta-selftest/recipes-test/devtool/devtool-test-local_6.03.bb

@@ -9,6 +9,7 @@ SRC_URI = "http://downloads.yoctoproject.org/mirror/sources/syslinux-${PV}.tar.x
 
 SRC_URI[md5sum] = "92a253df9211e9c20172796ecf388f13"
 SRC_URI[sha256sum] = "26d3986d2bea109d5dc0e4f8c4822a459276cf021125e8c9f23c3cca5d8c850e"
+UPSTREAM_VERSION_UNKNOWN = "1"
 
 S = "${WORKDIR}/syslinux-${PV}"