Say nothing more on a step's log after one publish fails, so a bus that does not take its lines costs a step at most one timeout and never fails it

go/buildstep/step_test.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"encoding/json"
 	"errors"
+	"fmt"
 	"sync"
 	"testing"
 	"time"
@@ -90,6 +91,17 @@ func TestStepEndsPassedFailedOrRefusedOnItsKey(t *testing.T) {
 		{"no whole output", func(context.Context) (any, error) {
 			return map[string]any{"failed": []map[string]string{{"package": "p", "full_output": "all of it"}}}, nil
 		}, delivery.StepPassed, "", `{"failed":[{"package":"p"}]}`},
+		// A log the bus does not take is tried once in a step, then left: the step passes, its failures name no step.
+		{"a dead log", func(context.Context) (any, error) {
+			tries := 0
+			l := &stepLog{say: func(string, any) error { tries++; return errors.New("timeout") }, id: "s1", run: "r1"}
+			raw := l.narrate(json.RawMessage(`{"failed":[{"package":"p","full_output":"a"},{"package":"q","full_output":"b"}]}`), nil)
+			raw = l.narrate(raw, nil)
+			if tries != 1 {
+				return nil, fmt.Errorf("%d publishes, want one", tries)
+			}
+			return raw, nil
+		}, delivery.StepPassed, "", `{"failed":[{"package":"p"},{"package":"q"}]}`},
 		{"error", func(context.Context) (any, error) { return nil, errors.New("exit 2") }, delivery.StepFailed, "exit 2", ""},
 		{"refusal", func(context.Context) (any, error) {
 			return nil, &Refusal{Text: "go 1.27.1 installed, the recipe builds with go 1.27.0", Want: "1.27.0", Have: "1.27.1"}