Spurious "update failed" message when applying an IMPORT change set

[amcinnes]

I created a change set with type IMPORT, using the AWS CLI. When applying this change set with stackup, the final state of the stack is IMPORT_COMPLETE. This is a success, but stackup prints a spurious update failed error because the state doesn't match this regex.

Example command and output:

$ stackup angus-tgw-demo change-set apply --name import
INFO: [03:14:26] angus-tgw-demo - IMPORT_IN_PROGRESS - User Initiated
INFO: [03:14:29] TransitGatewayVpcAttachment - IMPORT_IN_PROGRESS - Resource import started.
INFO: [03:14:30] TransitGatewayVpcAttachment - IMPORT_IN_PROGRESS
INFO: [03:14:30] TransitGatewayVpcAttachment - IMPORT_COMPLETE - Resource import completed.
INFO: [03:14:32] TransitGatewayVpcAttachment - UPDATE_IN_PROGRESS - Apply stack-level tags to imported resource if applicable.
INFO: [03:14:49] TransitGatewayVpcAttachment - UPDATE_COMPLETE
INFO: [03:14:51] angus-tgw-demo - IMPORT_COMPLETE
ERROR: update failed