does no build

get this error on windows

coredns>go build
go: finding github.com/coredns/fallback latest
go: finding github.com/coredns/coredns/plugin/proxy latest
go: finding github.com/coredns/coredns/plugin latest
go: github.com/mholt/caddy@v1.0.1: parsing go.mod: unexpected module path "github.com/caddyserver/caddy"
go: error loading module requirements

Start by reproducing the reported Windows failure with `go build`, then inspect the module requirements involved in the `github.com/mholt/caddy@v1.0.1` and `github.com/caddyserver/caddy` path error. Done means the fallback plugin builds successfully on Windows without the module-requirements error.

Written by the indexing model from the issue text.