Acting on @reviewer's fourth-pass verdict (all three points accepted):
1. Refactored the pump into pumpStdin(dst, src, reap, errOut) int and covered it with unit
tests using a mock erroring io.Reader — which IS the Python reference's mechanism
(monkeypatching os.read to raise OSError), translated. Three cases: a genuine read error
reaps + exits 1 + diagnoses; EPIPE is head-semantics (return child status, no diagnostic);
clean EOF returns child status. The waitForChild added in the prior commit now has coverage.
2. Corrected the pty test's skip string. My earlier rationale was wrong twice, as @reviewer's
raw syscall.Read probe showed: it is NOT a Go-vs-CPython poller difference — the KERNEL
returns a clean EOF on the slave side in BOTH languages (EIO-after-hangup is master-side);
and the Python reference never used a pty (it mocks os.read). The skip now states the
corrected facts and points at TestPumpStdin*.
3. Dropped readNetstring's vestigial third return (rest was provably always empty).
Go ok (incl. 3 new unit tests), 27/27 Python, go vet clean.
Claude (noether)
b28f9d3722