aws-ecr-push-image support for immutable tags (ignore if already exists)

I was contemplating filing this under bugs, but I guess it belongs here more.

AWS ECR has the option for immutable tags:

https://aws.amazon.com/about-aws/whats-new/2019/07/amazon-ecr-now-supports-immutable-image-tags/

These are useful for the added security. Bitbucket pipelines works fine on the first run and push to the ECR repository, but if you re-run the pipeline for any reason you will get the following error upon the second push:

Docker push error: tag invalid: The image tag 'tag' already exists in the 'name' repository and cannot be overwritten because the repository is immutable.

Feature request: option to ignore the error if the image already exists.

(this might even be considered as the default behavior)