FFU : ffwd-upgrade-prepare fails if you edit any existing or add new environment file in existing plan

Issue

During FFWD upgrade, openstack "overcloud ffwd-upgrade run" and it failed. Debugging it realized we have missed to include the one of the environment file to over-ride the repositories in FastForwardCustomRepoScriptContent. We updated the related environment file and when we re-executed the fwd-upgrade-prepare then it failed with the following error:

Waiting for messages on queue 'ffwdupgrade' with no timeout.
{u'config_name': u'ffwd-upgrade-prepare',
 u'execution': {u'created_at': u'2018-06-22 02:45:22',
                u'id': u'd05a82ef-c002-4f9b-9890-5d465a8a6bd2',
                u'input': {u'config': u'#!/bin/bash \nrm -f /usr/libexec/os-apply-config/templates/etc/os-net-config/config.json || true \n',
                           u'config_name': u'ffwd-upgrade-prepare',
                           u'group': u'script',
                           u'queue_name': u'ffwdupgrade',
                           u'server_name': u'overcloud-controller-0',
                           u'server_uuid': u'afb6d2a8-0937-488b-85dd-157ac38ad6bf'},
                u'name': u'tripleo.deployment.v1.deploy_on_server',
                u'params': {u'index': 1,
                            u'namespace': u'',
                            u'root_execution_id': u'9bbb254a-2b83-4047-8dd1-e92f672ceadd',
                            u'task_execution_id': u'ce79401a-09e8-4b35-baed-adc5ba6dc0d4'},
                u'spec': {u'input': [u'server_uuid',
                                     u'server_name',
                                     u'config',
                                     u'config_name',
                                     u'group',
                                     {u'queue_name': u'tripleo'}],
                          u'name': u'deploy_on_server',
                          u'tags': [u'tripleo-common-managed'],
                          u'tasks': {u'deploy_config': {u'action': u'tripleo.deployment.config',
                                                        u'input': {u'config': u'<% $.config %>',
                                                                   u'group': u'<% $.group %>',
                                                                   u'name': u'<% $.config_name %>',
                                                                   u'server_id': u'<% $.server_uuid %>'},
                                                        u'name': u'deploy_config',
                                                        u'on-complete': u'send_message',
                                                        u'publish': {u'status_code': u'<% task().result.deploy_status_code %>',
                                                                     u'stderr': u'<% task().result.deploy_stderr %>',
                                                                     u'stdout': u'<% task().result.deploy_stdout %>'},
                                                        u'publish-on-error': {u'message': u'<% task().result %>',
                                                                              u'status': u'FAILED'},
                                                        u'type': u'direct',
                                                        u'version': u'2.0'},
                                     u'send_message': {u'action': u'zaqar.queue_post',
                                                       u'input': {u'messages': {u'body': {u'payload': {u'config_name': u'<% $.config_name %>',
                                                                                                       u'execution': u'<% execution() %>',
                                                                                                       u'message': u'<% $.get("message", "") %>',
                                                                                                       u'server_name': u'<% $.server_name %>',
                                                                                                       u'server_uuid': u'<% $.server_uuid %>',
                                                                                                       u'status': u'<% $.get("status", "SUCCESS") %>',
                                                                                                       u'status_code': u'<% $.get("status_code", "") %>',
                                                                                                       u'stderr': u'<% $.get("stderr", "") %>',
                                                                                                       u'stdout': u'<% $.get("stdout", "") %>'},
                                                                                          u'type': u'tripleo.deployment.v1.deploy_on_server'}},
                                                                  u'queue_name': u'<% $.queue_name %>'},
                                                       u'name': u'send_message',
                                                       u'on-success': [{u'fail': u'<% $.get(\'status\') = "FAILED" %>'}],
                                                       u'retry': u'count=5 delay=1',
                                                       u'type': u'direct',
                                                       u'version': u'2.0'}},
                          u'version': u'2.0'},
                u'updated_at': u'2018-06-22 02:45:22'},
 u'message': u"Timeout for heat deployment 'ffwd-upgrade-prepare'",
 u'server_name': u'overcloud-controller-0',
 u'server_uuid': u'afb6d2a8-0937-488b-85dd-157ac38ad6bf',
 u'status': u'FAILED',
 u'status_code': u'',
 u'stderr': u'',
 u'stdout': u''}