The numbers from the rebased branch, and a second shape of test_dev flake

test_reload.exe 25 for 25 after the rebase and the reg_at change, with the
pre-fix binary refusing 4011 of 73306 runs beside it, so the window is known
racy rather than merely quiet.

test_dev flaked twice over while that ran, in two different shapes. Three runs
in six at load 21 were the stale-park rerun, which has a lane. Two of another
six were something else: most of the daemons in the file exiting before they
bound their socket, with no stale socket or daemon left behind, and six green
on a quiet machine after. Neither touches the registry — a daemon that dies
before binding died before any program it builds ran a line of flan_dev.c —
but the second shape does not seem to have been written down anywhere, so it
is written down here.

FIX.org

@@ -5631,6 +5631,29 @@ And independently, by the reviewer, on their own machine and harness: 9 of 72
 refused before under 24-way contention, 0 of 120 after, test_reload.exe 20 for
 20, and 10 for 10 again on the rebased merge.
 
+Re-run after the rebase and the [flan_dev_reg_at] change, same control
+arrangement: test_reload.exe 25 for 25, with the pre-fix binary refusing 4011
+of the 73306 runs it managed beside it.
+
+** Two shapes of test_dev flake seen while proving this, neither of them this
+Worth recording because the second one does not seem to have a name yet.
+Running test_dev.exe six times at load 21 gave three failures. All three were
+one shape — [rerun: the program is already running], cascading into every
+dev-rerun assertion after it — which is the stale-park in [flan_merged_rerun]
+(lib/dev.ml) that has its own lane.
+
+A second six-run batch, while the load average was still falling from that,
+gave two failures of a different shape: a daemon exiting with status 1 or 2
+"before binding /tmp/flan-devtest-*.sock", across most of the daemons in the
+file at once. No stale socket or leftover daemon was found afterwards. Six
+more runs on a genuinely quiet machine: six green.
+
+Neither is the registry and neither is this fix. A daemon that dies before it
+binds died on the OCaml side of the world, before any program it builds has
+run a line of flan_dev.c, and the rerun shape never reads the allocation table
+at all. They are noted here only so that the next person who sees red in
+test_dev under load has both shapes written down rather than one.
+
 ** It also hardens the address root, which was the same spin
 [flan_dev_reg_at] — the inspector's "what block is this address in" — calls
 the same [flan_reg_snap] and, unlike the listing, steps *past* a slot it could