Merge pull request #2621 from alicebob/devwatch

reset watch's lastIndex on error

watch/plan.go

@@ -57,6 +57,7 @@ OUTER:
 		if err != nil {
 			// Perform an exponential backoff
 			failures++
+			p.lastIndex = 0
 			retry := retryInterval * time.Duration(failures*failures)
 			if retry > maxBackoffTime {
 				retry = maxBackoffTime
@@ -85,6 +86,9 @@ OUTER:
 		if oldIndex != 0 && reflect.DeepEqual(p.lastResult, result) {
 			continue
 		}
+		if p.lastIndex < oldIndex {
+			p.lastIndex = 0
+		}
 
 		// Handle the updated result
 		p.lastResult = result