[WIP][linux_distributions][chromium_os] How to fix missing CHROMEOS_RELEASE_APPID

[LukeShortCloud]

This error occurs if copying an existing overlay (ex., overlay-amd64-generic), renaming it, and eventually trying to build an image for it.

(cr) ((ca80eae...)) <USER>@<HOSTNAME> ~/chromiumos/src/scripts $  ./build_image --board=${BOARD} --noenable_rootfs_verification
<OMITTED>
22:52:19.199: INFO: Detected the following DLCs: termina-dlc
22:52:19.199: INFO: Building image: DLC termina-dlc
22:52:19.200: INFO: Creating the DLC image.
build_dlc: Unhandled exception:
Traceback (most recent call last):
  File "/mnt/host/source/chromite/bin/build_dlc", line 208, in <module>
    DoMain()
  File "/mnt/host/source/chromite/bin/build_dlc", line 204, in DoMain
    commandline.ScriptWrapperMain(FindTarget)
  File "/mnt/host/source/chromite/lib/commandline.py", line 1037, in ScriptWrapperMain
    ret = target(argv[1:])
  File "/mnt/host/source/chromite/scripts/build_dlc.py", line 183, in main
    board=opts.board)
  File "/mnt/host/source/chromite/lib/dlc_lib.py", line 625, in InstallDlcImages
    dlc_generator.GenerateDLC()
  File "/mnt/host/source/chromite/lib/dlc_lib.py", line 510, in GenerateDLC
    self.CreateImage()
  File "/mnt/host/source/chromite/lib/dlc_lib.py", line 399, in CreateImage
    self.CreateSquashfsImage()
  File "/mnt/host/source/chromite/lib/dlc_lib.py", line 297, in CreateSquashfsImage
    self.SetupDlcImageFiles(squashfs_root)
  File "/mnt/host/source/chromite/lib/dlc_lib.py", line 317, in SetupDlcImageFiles
    self.PrepareLsbRelease(dlc_dir)
  File "/mnt/host/source/chromite/lib/dlc_lib.py", line 342, in PrepareLsbRelease
    (platform_lsb_rel_path, cros_set_lsb_release.LSB_KEY_APPID_RELEASE))
Exception: /build/cuos-amd64/etc/lsb-release does not have a valid key CHROMEOS_RELEASE_APPID