Has anyone successfully completed this procedure?
I should add that the document I am using it this one https://pantheon.io/docs/guides/drupal-9-migration/upgrade-to-d9#deploy-to-a-multidev
And the step I am stuck on it the Deploy step. When is says to merge "
master" I get git error “fatal: refusing to merge unrelated histories”
I’m thinking there must be an error in the instructions earlier on but I am not expert enough to be able to figure it out (plus I feel there should be a bit more information about this step and those that follow).