Judge a packaging module's news by plans that built it, over every plan since its build (hq ADR 0267, review)

A plan that closed without building a module hid a missed merge from it;
a window of recent plans let an old closure back in once the plan that
overtook it slid out; a merge the forge gave no time was acted on again
every pass. A plan answering the merge's own commit is now a look at it,
and clocks a little apart do not make a merge history.

cmd/mesh-controller/missed_merges.go

@@ -102,6 +102,11 @@ func catchUpOnMerges(ctx context.Context, now time.Time, announced merges,
 		return err
 	}
 	for _, a := range all {
+		// A merge the forge said no time of is dated by its announcement, so a packaging module's look can
+		// make it history once acted on, and the catch-up does not act on it again every pass (ADR 0267).
+		if a.SourceMoved.MergedAt == "" && !a.At.IsZero() {
+			a.SourceMoved.MergedAt = a.At.UTC().Format(time.RFC3339)
+		}
 		if now.Sub(a.At) < mergeGrace {
 			continue
 		}