Fix the dep on cenkalti

vendor/github.com/cenkalti/backoff/example_test.go

@@ -0,0 +1,73 @@
+package backoff
+
+import (
+	"log"
+
+	"golang.org/x/net/context"
+)
+
+func ExampleRetry() {
+	// An operation that may fail.
+	operation := func() error {
+		return nil // or an error
+	}
+
+	err := Retry(operation, NewExponentialBackOff())
+	if err != nil {
+		// Handle error.
+		return
+	}
+
+	// Operation is successful.
+}
+
+func ExampleRetryContext() {
+	// A context
+	ctx := context.Background()
+
+	// An operation that may fail.
+	operation := func() error {
+		return nil // or an error
+	}
+
+	b := WithContext(NewExponentialBackOff(), ctx)
+
+	err := Retry(operation, b)
+	if err != nil {
+		// Handle error.
+		return
+	}
+
+	// Operation is successful.
+}
+
+func ExampleTicker() {
+	// An operation that may fail.
+	operation := func() error {
+		return nil // or an error
+	}
+
+	ticker := NewTicker(NewExponentialBackOff())
+
+	var err error
+
+	// Ticks will continue to arrive when the previous operation is still running,
+	// so operations that take a while to fail could run in quick succession.
+	for _ = range ticker.C {
+		if err = operation(); err != nil {
+			log.Println(err, "will retry...")
+			continue
+		}
+
+		ticker.Stop()
+		break
+	}
+
+	if err != nil {
+		// Operation has failed.
+		return
+	}
+
+	// Operation is successful.
+	return
+}