mcs: fix panic of get leader

[rleungx]

What problem does this PR solve?

Issue Number: Close #7280.

What is changed and how does it work?

Check List

Tests

• Unit test

Release note

None.

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• JmPotato
• lhy1024

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[codecov]

Codecov Report

Merging #7472 (f82a0cd) into master (995fcef) will decrease coverage by 0.26%.
Report is 1 commits behind head on master.
The diff coverage is 100.00%.

❗ Current head f82a0cd differs from pull request most recent head e3d35c4. Consider uploading reports for the commit e3d35c4 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #7472      +/-   ##
==========================================
- Coverage   74.46%   74.21%   -0.26%     
==========================================
  Files         452      451       -1     
  Lines       49942    49728     -214     
==========================================
- Hits        37190    36906     -284     
- Misses       9412     9487      +75     
+ Partials     3340     3335       -5     

Flag	Coverage Δ
unittests	74.21% <100.00%> (-0.26%)	⬇️

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[lhy1024]

Do we need to cherry pick it?

[rleungx]

/merge

[ti-chi-bot]

@rleungx: It seems you want to merge this PR, I will help you trigger all the tests:

/run-all-tests

You only need to trigger /merge once, and if the CI test fails, you just re-trigger the test that failed and the bot will merge the PR for you after the CI passes.

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[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: f82a0cd

[CabinfeverB]

/merge

[ti-chi-bot]

@CabinfeverB: It seems you want to merge this PR, I will help you trigger all the tests:

/run-all-tests

You only need to trigger /merge once, and if the CI test fails, you just re-trigger the test that failed and the bot will merge the PR for you after the CI passes.

If you have any questions about the PR merge process, please refer to pr process.

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[CabinfeverB]

/run-all-tests

[CabinfeverB]

/hold

[CabinfeverB]

/hold cancel