Good catch, you are correct. I initially was going post the actual command for checking out a branch at a time:

> git checkout $(git rev-list -1 --before="YYYY-MM-DD" master)

but thought I found a shortcut - which turns out is not really one, and like you said: confusing.

I can't edit my post, but in any case; the point being: it would be nice if import statements are closer to "github.com/google/uuid@YYYY-MM-DD" or in this case you can pass a date to version: "YYYY-MM-DD" and the library would run the uglier nested command above to import the proper version.