Alias fails when passed to child module.

[hongkongkiwi]

Terraform does not correctly handle aliases for this provider when passing to child module.

Terraform v0.13.0
+ provider registry.terraform.io/terraform-providers/docker v2.7.2

For example, this will fail with error during terraform validate:
Error: missing provider provider["registry.terraform.io/hashicorp/docker"].foo

provider "docker" {
  alias = "foo"
  host = "tcp://127.0.0.1:2376/"
}

module "mycustommodule" {
  source = "./test2"
  providers = {
    docker = docker.foo
  }
}