I was developing a Clojure/ClojureScript Web site on Windows when I noticed this bug. In short, the compiler produced output paths for Google Closure dependencies that were not compatible with Windows so the builds could not pass.
I find it useful to create a entire project devoted to presenting, analyzing and fixing the problem. So for more info about the fix see the GitHub repo.
Thanks David Nolen and the rest of the good ClojureScript community members over on Clojurians slack channel for helping me land this contribution.
If you are interested in on what site I was working on, you can check it out here.
[Update 06.04.2021.] When I was working on this I’ve added one more jira that will probably never be merged. Adding it here just for reference.