Fix support for extra config values as mappings

salt/files/minion.d/f_defaults.conf

@@ -1255,7 +1255,7 @@ alternative.mongo.{{ name }}: {{ value }}
 
 {%- for configname in cfg_minion %}
 {%- if configname not in reserved_keys and configname not in default_keys %}
-  {%- if cfg_minion[configname] is iterable and cfg_minion[configname] is not string %}
+  {%- if cfg_minion[configname] is iterable and cfg_minion[configname] is not mapping and cfg_minion[configname] is not string %}
 {{ configname }}:
     {%- for item in cfg_minion[configname] %}
   - {{ item }}