test(t27): broaden the committed-output local-path guard to all platforms

/Users/ alone would miss /home/, /private/, /tmp/, and C:\Users
checkout prefixes if the notebook were ever re-executed elsewhere.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01W75ea3yFYQbjVhB2evhRiZ

Author: igerber

tests/test_t27_cic_distributional_effects_drift.py

@@ -438,10 +438,12 @@ def test_no_local_paths_in_committed_outputs(self):
         # The guardrail-variant warnings render in the committed output by
         # design, but the machine-specific checkout prefix is normalized
         # away before committing - rendered docs must not leak local
-        # usernames/paths.
+        # usernames/paths, whichever platform executed the notebook.
         from tests._tutorial_drift import notebook_output_text
 
-        assert "/Users/" not in notebook_output_text(NB)
+        text = notebook_output_text(NB)
+        for prefix in ("/Users/", "/home/", "/private/", "C:\\Users", "/tmp/"):
+            assert prefix not in text, f"committed output leaks a local path: {prefix!r}"
 
     def test_headline_claims_present_in_prose(self):
         md = notebook_markdown(NB)