Clear a module's fingerprint-not-composed on every successful take-in, and stop serve's goroutines before an error return undoes anything (issue 1945)

A success cleared the condition only when the same follower had raised it, so
one raised before a restart or by another follower stayed open after the take-in
worked, and the operator read that a build needed a look. Clearing a condition
that is not open costs one read. On an error return, serve now ends its
goroutines before the keeper closes and before handActConn and the bus are put
back (the review of fix 12).

cmd/mesh-controller/composed_keys.go

@@ -166,10 +166,12 @@ func followDoneKey(ctx context.Context, open *stores, module string) {
 		err := takeOnceInSlot(ctx, open, module)
 		o := doneKeyObservation(module)
 		if err == nil {
-			if keeper := conditionsFrom; keeper != nil && failed {
+			// Cleared on every success, whoever raised it: a controller before a restart or another follower (issue
+			// 1945). A condition that is not open costs one read.
+			if keeper := conditionsFrom; keeper != nil {
 				_, _ = keeper.Clear(ctx, o.Key(), "composed and granted")
-				failed = false
 			}
+			failed = false
 			if _, again := doneKeysLookAgain.LoadAndDelete(module); again {
 				continue // a wake came while this one ran: once more, for the key written meanwhile
 			}