Wrong list name in config file

salt/files/master.d/f_defaults.conf

 # Note that enabling this feature means that minions will not be
 # available to target for up to the length of the maintanence loop
 # which by default is 60s.
-{%- if cfg_minion['key_cache'] in cfg_master %}
+{%- if cfg_master['key_cache'] in cfg_master %}
 {{ get_config('key_cache', '') }}
 {% else %}
 #key_cache: ''