Bug report
See usesTime method of StringTemplateStyle class in logging module. It's passing self.asctime_format to fmt.find but I believe it should be passing self.asctime_search. The two variables have the same value so it doesn't currently result in broken behavior, but this is a latent bug that could reveal itself if either variable's value changes. I've got a PR ready, I'll submit it shortly after this.
Linked PRs