Ansible local_action: stat doesnt find my file

Ansible Tower uses PRoot which provides a cool interface for creating chroot and similar jails. In the Tower docs they state:

3.5. Playbooks missing access to necessary data due to PRoot issues

When running a playbook that reads and writes information in certain prohibited directories, users may encounter issues with PRoot. PRoot runs the ansible-playbook command within a chroot jail. In cases like these, the running playbook cannot see other playbooks or sensitive data on disk and should the playbook expect to have access to that information, problems will occur. To fine tune your usage of PRoot, there are certain variables that can be set:

# Enable proot support for running jobs (playbook runs only).
AWX_PROOT_ENABLED = False

# Command/path to proot.
AWX_PROOT_CMD = 'proot'

# Additional paths to hide from jobs using proot.
AWX_PROOT_HIDE_PATHS = []

# Additional paths to show for jobs using proot.
AWX_PROOT_SHOW_PATHS = []

FWIW, I had similar issues when trying to find files inside the role's 'files' directory (no Tower involved). I'd normally reference these as "../files/something", but that doesn't work for a local_action stat. Instead, this works:

- name: check for optional config file
  local_action: stat path={{ role_path }}/files/{{ inventory_hostname }}/some_file
  register: optional_file

(so I guess the moral of the story is: use a full path to the local file)