Minor upgrade fails on Controller node when using TLS with Octavia with The conditional check 'internal_tls_enabled|bool' failed in Red Hat OpenStack Platform 13

Issue

Minor upgrade fails on Controller node when using TLS with Octavia with:

TASK [remove TLS proxy if configured and running] ******************************
Thursday 11 July 2019  11:20:00 +0200 (0:00:00.102)       0:10:41.162 ********* 
fatal: [controller-2]: FAILED! => {"msg": "The conditional check 'internal_tls_enabled|bool' failed. The error was: error while evaluating conditional (internal_tls_enabled|bool): 'internal_tls_enabled' is undefined\n\nThe error appears to have been in '/var/lib/mistral/a34e8cd1-dbaf-4def-b091-2fb480f1694f/Controller2018/update_tasks.yaml': line 171, column 3, but may\nbe elsewhere in the file depending on the exact syntax problem.\n\nThe offending line appears to be:\n\n  when: step|int == 5\n- docker:\n  ^ here\n"}