Fix missing continuation indicator in ssl-opt.sh
diff --git a/tests/ssl-opt.sh b/tests/ssl-opt.sh
index cf2c168..597a5f1 100755
--- a/tests/ssl-opt.sh
+++ b/tests/ssl-opt.sh
@@ -4297,7 +4297,7 @@
              [ \$? -eq 1 ] &&
              $P_CLI force_ciphersuite=TLS-ECDHE-RSA-WITH-AES-128-CBC-SHA256" \
             0 \
-            -s "Async sign callback: using key slot 0"
+            -s "Async sign callback: using key slot 0" \
             -S "Async resume" \
             -s "Async cancel" \
             -s "! mbedtls_ssl_handshake returned" \