File README got renamed into README.md in the repository [1], causing dodoc statement in the dev-lang/go-9999 ebuild to fail. After the trivial fix, the build succeeds. [1] https://github.com/golang/go/commit/495e02db8c6e080504f03525daffa4c8f19a7b03 Reproducible: Always
This has been fixed, thanks for the report.