Unable to install pack from local directory

SUMMARY

Upon trying to install a known working pack from a local directory within the StackStorm Docker client container, the installation fails with ValueError: Local pack directory "/opt/stackstorm/test_pack" doesn't exist.

STACKSTORM VERSION

st2 3.6.0, on Python 3.6.9

OS, environment, install method

Docker container, using the official Docker Compose config. Host environment is Arch Linux running 5.17.5. All commands are executed from within the st2client container.

Steps to reproduce the problem

1. Obtain copy of working pack on local computer. The linked pack installs fine when installing directly from GitHub.
2. Copy local pack to st2client container: docker compose cp ~/repos/test_pack st2client:/opt/stackstorm/ (on host machine, from st2-docker directory)
3. Attempt to install pack: st2 pack install file:///opt/stackstorm/test_pack (from within st2client container)

Expected Results

The pack installs successfully, as it does when installing from GitHub.

Actual Results

Install fails with ValueError: Local pack directory "/opt/stackstorm/test_pack" doesn't exist. As a sanity check, the directory does exist:

root@667335d8ca8c:/opt/stackstorm# ls /opt/stackstorm
configs  exports  packs  packs.dev  rbac  st2  test_pack  virtualenvs

Thank you for any assistance!

Reproduce the failure inside the st2client container using the documented docker compose copy and st2 pack install file:///opt/stackstorm/test_pack commands. Start by tracing how the CLI validates local pack paths; done means the known working local pack installs successfully, matching installation from GitHub.