Clarify message of overloaded pending proposals for live loader. (#2732)

* Clarify message of overloaded pending proposals for live loader.

* Self review: Fix typo.

dgraph/cmd/live/batch.go

@@ -140,9 +140,9 @@ func handleError(err error) {
 		x.Fatalf(s.Message())
 	case strings.Contains(s.Message(), "x509"):
 		x.Fatalf(s.Message())
-	case strings.Contains(s.Message(), "Server unavailable."):
+	case strings.Contains(s.Message(), "Server overloaded."):
 		dur := time.Duration(1+rand.Intn(10)) * time.Minute
-		fmt.Printf("Server is unavailable. Will retry after %s.", dur.Round(time.Minute))
+		fmt.Printf("Server is overloaded. Will retry after %s.", dur.Round(time.Minute))
 		time.Sleep(dur)
 	case err != y.ErrAborted && err != y.ErrConflict:
 		fmt.Printf("Error while mutating %v\n", s.Message())

worker/proposal.go

@@ -101,7 +101,7 @@ func uniqueKey() string {
 }
 
 var errInternalRetry = errors.New("Retry Raft proposal internally")
-var errUnableToServe = errors.New("Server unavailable. Please retry later")
+var errUnableToServe = errors.New("Server overloaded with pending proposals. Please retry later.")
 
 // proposeAndWait sends a proposal through RAFT. It waits on a channel for the proposal
 // to be applied(written to WAL) to all the nodes in the group.