Is the artifact unique per branch and PR, as it is with Travis caches?
Based on the terse conversation at https://github.com/actions/download-artifact/issues/3, it looks like download-artifact is not a solution to caching across invocations of workflows.
My use case is a project using Go, where I would like to preserve GOCACHE from one Workflow invocation to another. This particular project is taking about 11 minutes to run `go test -race ./...`. If it could use the build cache from a previous run, I would expect it to take less than a minute, as many of the test results would be cached and most of the compilation results would be cached too.
Not being able to transfer GOCACHE between runs is a significant hindrance to adopting GitHub Actions.
Glad you guys are working on this as well, I use GitHub Actions to build some intermediary packages and caching is the only way to do it since artifacts won't really cut it for large objects. It'd take too long to upload.