selftests: net: lib: ignore possible errors

No need to disable errexit temporary, simply ignore the only possible
and not handled error.
Reviewed-by: Geliang Tang <geliang@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://lore.kernel.org/r/20240607-upstream-net-next-20240607-selftests-mptcp-net-lib-v1-1-e36986faac94@kernel.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

tools/testing/selftests/net/lib.sh

@@ -128,25 +128,17 @@ slowwait_for_counter()
 cleanup_ns()
 {
 	local ns=""
-	local errexit=0
 	local ret=0
 
-	# disable errexit temporary
-	if [[ $- =~ "e" ]]; then
-		errexit=1
-		set +e
-	fi
-
 	for ns in "$@"; do
 		[ -z "${ns}" ] && continue
-		ip netns delete "${ns}" &> /dev/null
+		ip netns delete "${ns}" &> /dev/null || true
 		if ! busywait $BUSYWAIT_TIMEOUT ip netns list \| grep -vq "^$ns$" &> /dev/null; then
 			echo "Warn: Failed to remove namespace $ns"
 			ret=1
 		fi
 	done
 
-	[ $errexit -eq 1 ] && set -e
 	return $ret
 }