TerraFrom bug 1

cat TTest/main.tf
provider "docker" {
    host = "tcp://127.0.0.1:2375/"
}

module "module1" {
    source = "./module1"
        module_enabled = "${var.module1_enabled}"
        docker_image = "milkfinch/jenkins"
}

module "module2" {
        source = "./module2"
        module_enabled = "${var.module2_enabled}"
        docker_image = "milkfinch/jenkins"
}

cat TTest/variables.tf
variable "module1_enabled" {
    description = "Is module1 enabled? (0|1)"
        default = 1
}

variable "module2_enabled" {
    description = "Is module2 enabled? (0|1)"
        default = 0
}

cat TTest/module1/variables.tf
variable "module_enabled" {}
variable "docker_image" {}

cat TTest/module2/variables.tf
variable "module_enabled" {}
variable "docker_image" {}

cat TTest/module1/main.tf
resource "docker_container" "module1" {
        count = "${var.module_enabled}"
    image = "${var.docker_image}"
    name = "module1_container"
}

cat TTest/module2/main.tf
resource "docker_container" "module2" {
    count = "${var.module_enabled}"
    image = "${var.docker_image}"
    name = "module2_container"
}

terraform apply

terraform destroy -target=module.module1
Do you really want to destroy?
  Terraform will delete the following infrastructure:
        module.module1
  There is no undo. Only 'yes' will be accepted to confirm

  Enter a value: yes

Error configuring: 1 error(s) occurred:

* 1:3: unknown variable accessed: var.module_enabled in:

${var.module_enabled}