_should_add_swapfile logic not honored during autoinstall

During autoinstall I have both a swap partition and btrfs root partition defined and I still end up with swap.img in my installed fstab. According to the logic in _should_add_swapfile both of these conditions should prevent adding a swapfile.

#cloud-config
autoinstall:
  version: 1
  storage:
    config:
    ### drive
    - id: disk0
      type: disk
      ptable: gpt
      grub_device: true
      preserve: false
      wipe: superblock
      match:
        size: largest
    ### partitions
    - id: efi_partition
      type: partition
      size: 512MB
      device: disk0
      flag: boot
      grub_device: true
      preserve: false
    - id: swap_partition
      type: partition
      size: 8GB
      device: disk0
      flag: swap
      preserve: false
    - id: root_partition
      type: partition
      size: -1
      device: disk0
      preserve: false
    ### format and mount efi partition
    - id: efi_format
      type: format
      fstype: fat32
      volume: efi_partition
      preserve: false
    - id: efi_mount
      type: mount
      path: /boot/efi
      device: efi_format
    ### format and mount swap partition
    - id: swap_format
      type: format
      fstype: swap
      volume: swap_partition
      preserve: false
    - id: swap_mount
      path: none
      type: mount
      device: swap_format
    ### format and mount root partition
    - id: root_format
      type: format
      fstype: btrfs
      volume: root_partition
      preserve: false
    - id: root_mount
      type: mount
      path: /
      device: root_format