fix a bug of branchGraph cache

[zjulcq]

fix a bug of branchGraph cache

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[zjulcq]

/test

[yusu1210]

fix a bug of branchGraph cache

具体的测试case能提供下吗

[zjulcq]

fix a bug of branchGraph cache

具体的测试case能提供下吗

好的，最近比较忙，等空了弄一下test_case，放到pullRequest中一起提交，届时再联系吧