Ignore error for making identical deals (data-preservation-programs#427)

In the case where provider failed to return success response,
Singularity will retry the same deal which may end up with being
rejected as boost has already received the same deal proposal.

This makes Singularity continue to next deal instead of keep retrying on
the same "identical deal" error message.

---------

Co-authored-by: liuziba <lisashane16@gmail.com>

service/dealpusher/dealpusher.go

@@ -2,6 +2,7 @@ package dealpusher
 
 import (
 	"context"
+	"strings"
 	"sync"
 	"time"
 
@@ -376,14 +377,21 @@ func (d *DealPusher) runSchedule(ctx context.Context, schedule *model.Schedule)
 					})
 				if err != nil {
 					Logger.Errorw("failed to send deal", "error", err, "provider", schedule.Provider)
+					if strings.Contains(err.Error(), "deal proposal is identical") {
+						return nil
+					}
 				}
+
 				return errors.WithStack(err)
 			}, retry.Attempts(d.sendDealAttempts), retry.Delay(time.Second),
 				retry.DelayType(retry.FixedDelay), retry.Context(ctx))
 			if err != nil {
 				return "", errors.Wrap(err, "failed to send deal")
 			}
 
+			if dealModel == nil {
+				continue
+			}
 			dealModel.ScheduleID = &schedule.ID
 
 			Logger.Debugw("save accepted deal", "deal", dealModel)