exec: Correct wrong "=" to "+=".

Change-Id: Iec8c1bb7a12ad7f2e1d4ac07c75482e4d86a0ea2
Refs: #1382

test/issues/1382/1382.sh

@@ -0,0 +1,31 @@
+#!/bin/sh
+# 1382.sh COPYRIGHT FUJITSU LIMITED 2020
+
+. $HOME/.mck_test_config
+
+BOOTPARAM="-c 12-15 -m 4G@4,4G@5,4G@6,4G@7 -O"
+USELTP=1
+FAIL=0
+LTPLIST="${PWD}/ltp_list.txt"
+
+. ../../common.sh
+
+echo "issue-1382 test run."
+
+pushd ${LTPBIN} > /dev/null
+while read line
+do
+	${MCEXEC} ./${line}
+	if [ $? -ne 0 ]; then
+		FAIL=1
+	fi
+done < ${LTPLIST}
+popd > /dev/null
+
+if [ ${FAIL} -eq 1 ]; then
+	echo "issue-1382 test NG."
+else
+	echo "issue-1382 test OK."
+fi
+
+mcstop