Since github provider v2.8.0 the github_repository_collaborator resource is broken.
It fails with User <username> is already a collaborator. In v2.7.0 this worked as expected.

Terraform Version

v0.12.25

Affected Resource(s)

• github_repository_collaborator

Terraform Configuration Files

resource "github_repository" "my_repo" {
  name        = "my_repo"
  private     = true
  description = ""
}

resource "github_repository_collaborator" "user_foobar" {
  repository  = github_repository.my_repo.name
  username   = "foobar"
  permission = "pull"
}

Panic Output

Expected Behavior

What should have happened?

The collaborator should be added to the repository and the resource should be in the state.

Actual Behavior

What actually happened?

The collaborator gets added to the repository with the correct permissions,
but terraform fails with this error and the resource is not in the state.

Error: User foobar is already a collaborator

  on test.tf line 7, in resource "github_repository_collaborator" "user_foobar":
  7: resource "github_repository_collaborator" "user_foobar" {

Steps to Reproduce

Please list the steps required to reproduce the issue, for example:

1. terraform apply

Important Factoids

References