Leave a module out of a send when the store lacks its image, and say it (issue 1742)

cmd/mesh-controller/signals.go

@@ -252,6 +252,14 @@ var signalsTable = []signalRow{
 		Kind: kindMovesHeld, Severity: conditions.Warning, Phase: 3,
 		needs: func(f *signalFacts) error { return f.heldErr }, watch: watchMovesHeld,
 		newest: func(f *signalFacts) time.Time { return time.Time{} }},
+	{Row: "S25", Signal: "a module left out of a send because the artifact store lacks an image it names",
+		Emitter: "controller's send", Trigger: "each send whose declaration names an image of the store that the store does not hold (novox/hq issue 1742)",
+		Bound: "none: raised on the first look at a registered build that names such an image, naming the module, each " +
+			"machine that runs it and the image; every send leaves that module out; the store is asked again at each " +
+			"look and the condition ends when it holds the image",
+		Kind: kindImageMissing, Severity: conditions.Warning, Phase: 3,
+		needs: func(f *signalFacts) error { return f.imagesErr }, watch: watchMissingImages,
+		newest: func(f *signalFacts) time.Time { return time.Time{} }},
 	{Row: "S20", Signal: "a send refused for the assignment generation it was composed from",
 		Emitter: "node-engine", Trigger: "each refusal (novox/hq issue 234)",
 		Bound: "none: raised at the first refusal, naming its sender, the generation it came from and the one the " +