On the surface, the py38 unit test error. But after further analysis, I found that the use cases of failure are all because stevedore cannot be loaded.

Here's what I do:
1、Analyzed the version of stevedore 4.1.1 looks like there is no problem.
2、Searched the merged code in watcher history, and found no suspicious points

The gerrit link: 871531

Looking forward to your reply.

Thanks!