The use-case here is that based on information in the /proc/cmdline certain actions can be taken.

A practical example in our case is that we have a play at the end of the provisioning phase that reboots the system. Since we don't want to accidentally reboot a system (or restart the network) on a production machine, having a way to separate an Anaconda post-install (sshd in chroot) with a normal system is a good way to make that distinction.

    ---
    - name: reboot
      hosts: all
      tasks:
      - action: command init 6
        only_if: "not '${ansible_cmdline.BOOT_IMAGE}'.startswith('$')"

A practical problem here is the fact that we cannot simply check whether it is set or empty:

    ---
    - name: reboot
      hosts: all
      tasks:
      - action: command init 6
        only_if: "'${ansible_cmdline.BOOT_IMAGE}'"

If ansible_cmdline was a string, a simple only_if: "'${ansible_cmdline}'.find(' BOOT_IMAGE=')" was an option, but still not very "beautiful" :-/

This implementation uses shlex.split() and uses split(sep, maxsplit=1).