AttributeError: 'set' object has no attribute 'extend'

[jan-matejka]

  File "/home/alex/.local/venv/podman-compose-1.6.0/bin/podman-compose", line 8, in <module>
    sys.exit(main())
             ~~~~^^
  File "/home/alex/git/3rd/podman-compose/main/podman_compose.py", line 4972, in main
    asyncio.run(async_main())
    ~~~~~~~~~~~^^^^^^^^^^^^^^
  File "/usr/lib/python3.13/asyncio/runners.py", line 195, in run
    return runner.run(main)
           ~~~~~~~~~~^^^^^^
  File "/usr/lib/python3.13/asyncio/runners.py", line 118, in run
    return self._loop.run_until_complete(task)
           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^
  File "/usr/lib/python3.13/asyncio/base_events.py", line 725, in run_until_complete
    return future.result()
           ~~~~~~~~~~~~~^^
  File "/home/alex/git/3rd/podman-compose/main/podman_compose.py", line 4967, in async_main
    await podman_compose.run()
  File "/home/alex/git/3rd/podman-compose/main/podman_compose.py", line 2373, in run
    self._parse_compose_file()
    ~~~~~~~~~~~~~~~~~~~~~~~~^^
  File "/home/alex/git/3rd/podman-compose/main/podman_compose.py", line 2685, in _parse_compose_file
    resolve_extends(services, [name for _, name in service_names], self.environ)
    ~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/alex/git/3rd/podman-compose/main/podman_compose.py", line 2246, in resolve_extends
    new_service = rec_merge({}, from_service, service)
  File "/home/alex/git/3rd/podman-compose/main/podman_compose.py", line 2198, in rec_merge
    ret = rec_merge_one(target, source)
  File "/home/alex/git/3rd/podman-compose/main/podman_compose.py", line 2181, in rec_merge_one
    value.extend(value2)
    ^^^^^^^^^^^^
AttributeError: 'set' object has no attribute 'extend'

The value2 is {<podman_compose.ServiceDependency object at 0x7fb276394f50>}

I'm unable to produce sscce for compose.yaml at this time.
pc version 1.5.0 works with the same compose.yaml.

podman-compose version 1.6.0
podman version 5.4.2

Environment:

• OS: Linux

[jan-matejka]

Introduced by 4aa11de
Reverting the commit seems to fix the issue, at least as far as pc config is concerned.