build|composite: use -x grep

build/common.sh

@@ -712,7 +712,7 @@ check_packages()
 		return 1
 	fi
 
-	DONE=$(tar tf ${PACKAGESET} | grep "^\./\.${SELF}_done\$" || true)
+	DONE=$(tar tf ${PACKAGESET} | grep -x "\./\.${SELF}_done" || true)
 	if [ -n "${DONE}" ]; then
 		return 0
 	fi

composite/distribution.sh

@@ -34,7 +34,7 @@ if [ ! -f "${PACKAGESET}" ]; then
 	exit 1
 fi
 
-COREFILE=$(tar -tf ${PACKAGESET} | grep "^./All/${PRODUCT_CORE}-[0-9].*\.txz$")
+COREFILE=$(tar -tf ${PACKAGESET} | grep -x "\./All/${PRODUCT_CORE}-[0-9].*\.txz")
 
 if [ -z "${COREFILE}" ]; then
 	echo ">>> Cannot continue without core package: ${PRODUCT_CORE}"