consumer stub logic don't run when config multi registries

[lunda1]

• I have searched the issues of this repository and believe that this is not a duplicate.
• I have checked the FAQ of this repository and believe that this is not a duplicate.

Environment

• Dubbo version: 2.6.5
• Operating System version: Windows 7
• Java version: 1.8.0_31

Steps to reproduce this issue

1. API的方式配置两个registry地址，例如： registryConfig.setAddress("127.0.0.1:2181|127.0.0.1:2182")。

2. API的方式配置ReferenceConfig按照文档配置stub，例如： referenceConfig.setStub("com.liupeng.dubbo.api.MyStub")。

3.API的方式启动consumer。

Pls. provide [GitHub address] to reproduce this issue.

Expected Result

What do you expected from the above steps？

Actual Result

What actually happens?

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