Make sure system.purge_repos is optional
diff --git a/linux/system/repo.sls b/linux/system/repo.sls
index 2ba2114..80fef35 100644
--- a/linux/system/repo.sls
+++ b/linux/system/repo.sls
@@ -183,7 +183,7 @@
     - user: root
     - group: root
     - mode: 0644
-{%- if system.purge_repos %}
+{%- if system.purge_repos|default(False) %}
     - replace: True
 {%- endif %}
     - defaults: