The two-process daemon took the same signal, and has no test that says so

docs/handoffs/HANDOFF-emacs-flake.md

@@ -59,6 +59,16 @@ block: eight hit-and-run connections, then a request proving the session is
 still there and still knows what it installed. Against the parent of the fix it
 fails with `killed by SIGPIPE`.
 
+**Both transports, and only one of them has a test.** `ignore_sigpipe` is
+called from two places and the suite's daemons are all merged, so the check
+above covers `merged_setup` and nothing covers `two_process` — which NEXT.md
+describes as the escape hatch for a machine that cannot build the compiler
+object, so it is live code somewhere. Driven by hand: before the fix a
+`--two-process` daemon dies on the *first* hit-and-run connection with status
+141 and leaves its socket behind, exactly as the merged one does; after it,
+a hundred of them leave it serving and answering `describe`. If that call site
+is ever removed, nothing in `dune test` will say so.
+
 ## The fix
 
 `lib/dev.ml`, three parts: