Python tier: 3 tests fail on Linux (platform assumptions, not real defects) nf-i69i ← Beads

Twinned from https://github.com/cfsh/ninefold/issues/550 by tools/beads/import_github.py's reconcile pass.

Filed unclaimed and unlabelled — inert backlog, per CLAUDE.md. Found while standing up the WSL office box (~/nf/ninefold), not while working a chunk.

What

./presubmit.py --suite python on Linux: 528 tests, 3 failures. All three fail on unmodified main — verified by stashing and re-running — so they are properties of the box, not a regression.

``` FAIL: test_a_child_that_imports_nflib_can_print_these_glyphs (test_nflib_proc) FAIL: test_doctor_detects_a_broken_interpreter_by_RUNNING_it (test_presubmit) FAIL: test_registration_matching_is_case_insensitive_on_windows (test_rebuild_f5) ```

The third names its own assumption. worktree_registered matches paths case-insensitively because NTFS does; the test asserts that behaviour against C:/fake/ninefold-c-f5, and on Linux the match correctly returns False.

The first two most likely fail because bare python does not exist on this box (only python3) — both spawn an interpreter. Worth confirming rather than assuming; the doctor test in particular is *about* interpreter detection, so a Linux failure there could be either the missing binary or a genuinely Windows-shaped assertion.

Why it might matter

Right now, nothing: the WSL box is documented as a coordination tier that does not gate code (see PR #549), and every other environment is Windows, where the suite is green.

It matters if the answer to "should the WSL box become a real dev box?" is yes. The Python tier is the one lane that already runs there, and it is not green — so "install dotnet and Godot in WSL and get --doctor green" would not by itself produce a passing presubmit. That is the decision this issue is really input to.

Shape of a fix, if it is ever activated

Not obviously "make them pass". Plausibly:

• Skip the case-insensitivity test off Windows (@unittest.skipUnless(os.name == "nt", ...)) — it is asserting an NTFS property, and asserting it on ext4 is asserting something false.
• For the two interpreter tests, decide whether bare python is a precondition (in which case --doctor already reports it and the tests could skip on its absence) or an assumption to remove.

Either way the useful outcome is that a Linux run reports *"3 skipped, platform"* rather than *"3 failed"* — a red suite that is expected-red trains people to ignore it, which is the actual cost here.

Repro

```bash cd <clone> # on Linux, without bare python on PATH ./presubmit.py --suite python ```

Environment: WSL2 Ubuntu, Python 3.14.4, no dotnet/godot/shellcheck.