fix python packages logic to account for the fact that ls-files doesn't list directories

[neilfulwiler]

this was an oversight on my part because I thought git ls-files . would include directories. I thought I had verified the resulting packages but I guess was confused because we still traverse explicit packages that are listed. This fixes like in https://app.graphite.dev/github/pr/dagster-io/internal/12014/alerts-fix-build-by-adding-logging-statement-back where we weren't running dagit tests after backend changed

Test Plan

From github.com:dagster-io/dagster
 * branch                  master     -> FETCH_HEAD
2024-10-03 16:06:38 INFO     Changed files between origin/master (b52d3147e8) and HEAD (e51c353592):
2024-10-03 16:06:38 INFO       - python_modules/dagster-webserver/dagster_webserver/graphql.py
2024-10-03 16:06:38 INFO     Finding Python packages:
2024-10-03 16:06:38 INFO       - REPO_NAME_PLACEHOLDER
2024-10-03 16:06:38 INFO       - assets_dbt_python
2024-10-03 16:06:38 INFO       - assets_dynamic_partitions
2024-10-03 16:06:38 INFO       - assets_modern_data_stack
2024-10-03 16:06:38 INFO       - assets_pandas_pyspark
2024-10-03 16:06:38 INFO       - assets_pandas_type_metadata
2024-10-03 16:06:38 INFO       - assets_smoke_test
2024-10-03 16:06:38 INFO       - assets_yaml_dsl
2024-10-03 16:06:38 INFO       - automation
2024-10-03 16:06:38 INFO       - builtin-blueprints
2024-10-03 16:06:38 INFO       - custom-blueprints
2024-10-03 16:06:38 INFO       - dagit
2024-10-03 16:06:38 INFO       - dagster
2024-10-03 16:06:38 INFO       - dagster
2024-10-03 16:06:38 INFO       - dagster-airbyte
2024-10-03 16:06:38 INFO       - dagster-airflow
2024-10-03 16:06:38 INFO       - dagster-airlift
2024-10-03 16:06:38 INFO       - dagster-aws
2024-10-03 16:06:38 INFO       - dagster-azure
...
2024-10-03 16:06:41 INFO     Building dagster-cloud-dagit because of changes to {PythonPackage(dagster-webserver)}
2024-10-03 16:06:41 INFO     Building dagster-cloud-dagit because of changes to {PythonPackage(dagster-webserver)}
2024-10-03 16:06:41 INFO     Building dagster-cloud-dagit because of changes to {PythonPackage(dagster-webserver)}
2024-10-03 16:06:41 INFO     Building dagit because we're building dagster-cloud-dagit

[neilfulwiler]

Merge activity

• Oct 3, 7:37 PM EDT: @neilfulwiler started a stack merge that includes this pull request via Graphite.
• Oct 3, 7:37 PM EDT: @neilfulwiler merged this pull request with Graphite.