regression: test-core#src:test/test_rust_chess_perft_full.rs red at f5c8fbec6016 (auto-filed by twatch)

• Type: regression (auto-filed by Track T watcher, host borg). Untriaged.
• Found: 2026-07-18T18:44:28Z
• Test source: test/test_rust_chess_perft_full.rs

Repro

tools/testmgr.py --tier native --job 'test-core#src:test/test_rust_chess_perft_full.rs' at f5c8fbec60164b1b6c0c220a12d66f744050bd04

Range

bad f5c8fbec6016, last good 2dffbb7c65a2, 4 commit(s) in range — the watcher narrows this by idle bisect; check tstate/TSTATE.md for the current range.

Log tail

pascal26:16: error: compiler error: div-zero stub not emitted but a div site needs it ()
  near:  sq     >>>  rank_of  

Stub ticket: signal only. Track T agent (face 2) enriches or a dev track takes it from the repro line.