The indexer wrote mesh-catalog's merge 9cdac09a back over the later 69056948,
rolling kernel and mesh-build-image back on the nodes: a merged message's
commit was written whatever the held one was. Before writing or deleting a
module's value, the indexer now asks the forge whether the merge contains the
held commit, keeps the held value when it does not and says so, and leaves the
message for redelivery when the forge cannot say. Each applied merged message
is said in one line with the modules written.
No tool showed what the indexer heard of FORGE nor a modules key's history
with times, so the cause could not be proven: the indexer now records each
FORGE message it handles (sequence, deliveries, times, commit, outcome) in its
state heard, read by indexer_heard, and indexer_module_history reads
modules.<module>'s kept values with their times.
Quick fix (Src order in writeOverlay) rejected: Src is 0 once the source moved
on, as here. Thorough fix chosen: the order is the forge's, on every path that
writes a module (merged message, take-in).