[Bugfix] Fix local speculators with dots in the name from classifying as custom_class

[mgoin]

Purpose

Fix speculative config so draft model names with dots (e.g. local GLM-5.2-speculator.dspark folder) are not misclassified as custom_class import paths.

Test Plan

Test Result

Before:

vllm serve zai-org/GLM-5.2-FP8 --max-model-len 20k --spec-model GLM-5.2-speculator.dspark --spec-method dspark --spec-tokens 7 -tp 4
...
ImportError: Cannot import module 'GLM-5.2-speculator' for custom proposer 'GLM-5.2-speculator.dspark': No module named 'GLM-5'

After: loads normally, same as using RedHatAI/GLM-5.2-speculator.dspark for the model

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Essential Elements of an Effective PR Description Checklist

• The purpose of the PR, such as "Fix some issue (link existing issues this PR will resolve)".
• The test plan, such as providing test command.
• The test results, such as pasting the results comparison before and after, or e2e results
• (Optional) The necessary documentation update, such as updating supported_models.md and examples for a new model.

[claude]

Claude Code Review

This pull request is from a fork — automated review is disabled. A repository maintainer can comment @claude review to run a one-time review.

[mergify]

Hi @mgoin, the pre-commit checks have failed. Please run:

uv pip install pre-commit>=4.5.1
pre-commit install
pre-commit run --all-files

Then, commit the changes and push to your branch.

For future commits, pre-commit will run automatically on changed files before each commit.

[yewentao256]

LGTM, thanks for the work!