`--changed-dependents=transitive` does not detect Python dependents after files are deleted

[bonauer-pf]

Describe the bug

• have foo.py and foo_test.py in the repo, with the test importing the foo module
• delete foo.py
• run pants --changed-since=main --changed-dependents=transitive check

Expected behavior:

• type checking should run on foo_test.py and should fail due to the unknown import of foo

Actual behavior:

• pants prints a warning about being unable to infer the dependencies of the foo import, but the check goal succeeds

The same problem applies to pants test: I expect foo_test.py to be executed, but it is not.

Pants version
2.31.0.dev3 with the pants.backend.experimental.python.typecheck.pyright backend

OS
tested on Linux

[cburroughs]

See also #13232 & #17512

[bonauer-pf]

@cburroughs thanks for the pointer!

I don't believe requiring to set [python-infer].unowned_dependency_behavior = "error", as mentioned in #17512, is a solution, since that is a global flag.

We have lots of experimental code in our monorepo that is intentionally "breakable", where we disable type checking via skip_pyright and don't run any tests. Setting this global flag would require all code in there to be 100% clean with no references to deleted code.

Happy to continue the discussion over on #17512 to avoid duplicates, though