Say a registry came back only when the call worked, and retry from toRetry's set (issue 457 review)

The streaming blob PUT is left unwaited, with why, since its body cannot be
read twice and the POST before it already waited.

cmd/mesh-controller/plan_retry.go

@@ -289,21 +289,23 @@ func retryPlan(ctx context.Context, open *stores, id string) (string, error) {
 		}
 	}
 	// Settled from the build records before anything is judged (novox/hq issue 457): a build of the tier
-	// that failed after the plan did is as failed as the one that failed it.
+	// that failed after the plan did is as failed as the one that failed it. What toRetry says is the
+	// failed set every step below works from.
+	var failed []string
 	if p.Tier < len(p.Tiers) {
 		recorded, byID, err := recordsOfAsked(ctx, inv, &p, p.Tiers[p.Tier])
 		if err != nil {
 			return "", err
 		}
-		toRetry(&p, recorded, byID)
+		failed = toRetry(&p, recorded, byID)
 	}
 	if err := retryRefusal(p, plans); err != nil {
 		return "", err
 	}
-	if again := unjudgedAtGate(p); len(failedIn(p)) == 0 && len(again) > 0 {
+	if again := unjudgedAtGate(p); len(failed) == 0 && len(again) > 0 {
 		return retryTierWhole(ctx, open, &p, again)
 	}
-	if len(failedIn(p)) == 0 {
+	if len(failed) == 0 {
 		return retryRollouts(ctx, open, &p)
 	}
 	entries, err := inv.Catalogued(ctx)
@@ -314,7 +316,6 @@ func retryPlan(ctx context.Context, open *stores, id string) (string, error) {
 	for _, e := range entries {
 		byName[e.Manifest.Module] = e
 	}
-	failed := failedIn(p)
 	var asked []string
 	for _, m := range failed {
 		askModule(ctx, &p, m, byName)