cmd/gomote: add experimental flag for bootstrapping with golangbuild

This change adds an experimental flag to the gomote service which
enables bootstrapping with through the use of golangbuild.

Change-Id: Ieb6045edd23bc04bf3a253c2d19ec6d03de0a0a5
Reviewed-on: https://go-review.googlesource.com/c/build/+/565418
Auto-Submit: Carlos Amedee <carlos@golang.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
diff --git a/internal/gomote/swarming_test.go b/internal/gomote/swarming_test.go
index baa4b5c..ff382c3 100644
--- a/internal/gomote/swarming_test.go
+++ b/internal/gomote/swarming_test.go
@@ -1159,7 +1159,7 @@
 				return
 			}
 		},
-	}); err == nil || !strings.Contains(err.Error(), "revdial.Dialer closed") {
+	}, false); err == nil || !strings.Contains(err.Error(), "revdial.Dialer closed") {
 		errCh <- fmt.Errorf("startNewSwarmingTask() = bc, %s; want \"revdial.Dialer closed\" error", err)
 	}
 	select {