iptables is needed thus install.

See merge request nexedi/slapos.package!175

playbook/wendelin-standalone-test.yml

@@ -12,3 +12,4 @@
   roles:
     - standalone-shared
     - { role: package, package_name: socat, package_state: present }
+    - { role: package, package_name: iptables, package_state: present }