[trainer,megatron] fix: super tiny fix the issue of repeatedly importing the mindspeed patch

[ji-huazhong]

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[gemini-code-assist]

Code Review

This pull request refactors the import of the optional mindspeed patch to a central location, which is a good improvement for handling optional dependencies. My review points out that this refactoring has made the try...except block in verl/workers/megatron_workers.py redundant. I've included a suggestion to remove this block to simplify the code and improve clarity.

[gemini-code-assist]

The try...except ImportError block is now redundant. The verl.workers.engine.mindspeed.transformer_impl module handles the case where mindspeed is not installed by setting repatch to None. Therefore, this import will no longer raise an ImportError under normal circumstances, and this try...except block can be removed to improve code clarity.

from verl.workers.engine.mindspeed.transformer_impl import repatch

[ji-huazhong]

The failed test cases are caused by network issues and are irrelevant to this PR.

• https://github.com/volcengine/verl/actions/runs/20614222265/job/59203935879?pr=4751
• https://github.com/volcengine/verl/actions/runs/20614222311/job/59203942232?pr=4751

I will fix these flaky CI issues in a subsequent PR.

[vermouth1992]

The failed test cases are caused by network issues and are irrelevant to this PR.

• https://github.com/volcengine/verl/actions/runs/20614222265/job/59203935879?pr=4751

• https://github.com/volcengine/verl/actions/runs/20614222311/job/59203942232?pr=4751

I will fix these flaky CI issues in a subsequent PR.

Those tests have been fixed on main.