Unable to install wf-migrate: HTTP 502 from code.as/core/socks

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I am trying to use wf-migrate to migrate my blog to a new WriteFreely installation. Running the installation command from the readme gives the following error message:

$ go get github.com/writefreely/wf-migrate/cmd/wfimport
go: downloading code.as/core/socks v1.0.0
go: github.com/writeas/go-writeas/v2@v2.1.0 requires
	code.as/core/socks@v1.0.0: unrecognized import path "code.as/core/socks": reading https://code.as/core/socks?go-get=1: 502 Bad Gateway

I hope the problem is temporary, but the Wayback Machine seems to show that code.as has been down since at least August (or at least it was down in August, and is now down again). Is there some workaround to this problem? Perhaps the offending repository is also hosted somewhere more stable and could be fetched from there instead?

As an aside, I was quite surprised to find that it's possible to export a JSON dump of my blog, but not import it, through the web interface.