Fix condition

Author: UnderGreen

tasks/install.debian.yml

@@ -23,7 +23,7 @@
   when: (mongodb_package == 'mongodb-org' and
         (mongodb_version is not defined
          or mongodb_repository[mongodb_major_version] is not defined
-         or mongodb_version != "3.6"))
+         or mongodb_version != "3.6") and ansible_distribution_release == "stretch")
 
 - name: Fail when used wrong mongodb_version variable
   fail: