Use ErrUnexpectedStatus more consistently

Signed-off-by: Ilya Dmitrichenko <errordeveloper@gmail.com>

remotes/docker/pusher.go

@@ -354,7 +354,7 @@ func (pw *pushWriter) Commit(ctx context.Context, size int64, expected digest.Di
 	switch resp.StatusCode {
 	case http.StatusOK, http.StatusCreated, http.StatusNoContent, http.StatusAccepted:
 	default:
-		return errors.Errorf("unexpected status: %s", resp.Status)
+		return remoteserrors.NewUnexpectedStatusErr(resp.Response)
 	}
 
 	status, err := pw.tracker.GetStatus(pw.ref)