Cloudformation waitForStackCreation error

Hi,

We use AWS Cloudformation Create/Update VSTS task to create a stack. The VSTS task waits for the stack status to become "Create_Complete". However, we have noticed that our stack status ends up as "Update_Complete" after becoming "Create_Complete" for a short while (less than 30 seconds).

As a result of the above, the "waitForStackCreation" method throws an exception as the method checks for the stack status every 30 seconds and it misses the stack status that is only there for a short while before becoming "Update_Complete". Please see the stack events below, you will notice that the "Create_Complete" status for AWS::Cloudformation:Stack type changes quickly to "Update_Complete".

28/08/2018 | Status | Type | Logical ID | Status Reason
-- | -- | -- | -- | --
  | 13:08:51 UTC+0100 | UPDATE_COMPLETE | AWS::CloudFormation::Stack | licensingserver-533 |  
  | 13:08:50 UTC+0100 | UPDATE_COMPLETE_CLEANUP_IN_PROGRESS | AWS::CloudFormation::Stack | licensingserver-533 |  
  | 13:08:48 UTC+0100 | UPDATE_COMPLETE | AWS::EC2::Instance | EC2Instance |  
  | 13:08:31 UTC+0100 | UPDATE_IN_PROGRESS | AWS::EC2::Instance | EC2Instance |  
  | 13:08:26 UTC+0100 | UPDATE_COMPLETE | AWS::EC2::Volume | NewVolume |  
  | 13:08:11 UTC+0100 | UPDATE_IN_PROGRESS | AWS::EC2::Volume | NewVolume |  
  | 13:07:58 UTC+0100 | UPDATE_IN_PROGRESS | AWS::CloudFormation::Stack | licensingserver-533 | User Initiated
  | 13:07:53 UTC+0100 | CREATE_COMPLETE | AWS::CloudFormation::Stack | licensingserver-533 |  
  | 13:07:50 UTC+0100 | CREATE_COMPLETE | AWS::CloudFormation::WaitCondition | EC2InstanceWaitCondition |  
  | 12:37:38 UTC+0100 | CREATE_IN_PROGRESS | AWS::CloudFormation::WaitCondition | EC2InstanceWaitCondition | Resource creation Initiated
  | 12:37:38 UTC+0100 | CREATE_IN_PROGRESS | AWS::CloudFormation::WaitCondition | EC2InstanceWaitCondition |  
  | 12:37:34 UTC+0100 | CREATE_COMPLETE | AWS::EC2::Instance | EC2Instance |  
  | 12:36:54 UTC+0100 | CREATE_IN_PROGRESS | AWS::EC2::Instance | EC2Instance | Resource creation Initiated
  | 12:36:53 UTC+0100 | CREATE_IN_PROGRESS | AWS::EC2::Instance | EC2Instance |  
  | 12:36:49 UTC+0100 | CREATE_COMPLETE | AWS::EC2::Volume | NewVolume |  
  | 12:36:37 UTC+0100 | CREATE_COMPLETE | Custom::AMIInfo | AMIInfo |  
  | 12:36:37 UTC+0100 | CREATE_IN_PROGRESS | Custom::AMIInfo | AMIInfo | Resource creation Initiated
  | 12:36:33 UTC+0100 | CREATE_IN_PROGRESS | AWS::EC2::Volume | NewVolume | Resource creation Initiated
  | 12:36:32 UTC+0100 | CREATE_IN_PROGRESS | AWS::EC2::Volume | NewVolume |  
  | 12:36:32 UTC+0100 | CREATE_IN_PROGRESS | Custom::AMIInfo | AMIInfo |  
  | 12:36:31 UTC+0100 | CREATE_COMPLETE | AWS::CloudFormation::WaitConditionHandle | EC2InstanceWaitConditionHandle |  
  | 12:36:31 UTC+0100 | CREATE_IN_PROGRESS | AWS::CloudFormation::WaitConditionHandle | EC2InstanceWaitConditionHandle | Resource creation Initiated
  | 12:36:31 UTC+0100 | CREATE_IN_PROGRESS | AWS::CloudFormation::WaitConditionHandle | EC2InstanceWaitConditionHandle |  
  | 12:36:28 UTC+0100 | CREATE_IN_PROGRESS | AWS::CloudFormation::Stack | licensingserver-533 |  

Start at the waitForStackCreation method in the VSTS CloudFormation Create/Update task and review how it polls stack status. Reproduce the reported transition from CREATE_COMPLETE to UPDATE_COMPLETE, then verify that the task completes successfully when that transition occurs between polls.

Written by the indexing model from the issue text.