Can't import module. Problem with go.mod?

go version: 1.12.7

repro steps:

create a temporary directory and cd into it
create this example main.go file:
```
package main
```

import( "fmt"

"github.com/grailbio/go-netdicom"
"github.com/grailbio/go-netdicom/dimse"

)

func main() { s, err := netdicom.NewServiceProvider(netdicom.ServiceProviderParams{CEcho: cEcho}, ":3000") if err != nil { panic(err) } s.Run() }

func cEcho(conn netdicom.ConnectionState) dimse.Status { fmt.Println("C-ECHO call") return dimse.Success }

- run `go mod init foo`
- run `go build .`

**result:**

go: finding github.com/grailbio/go-netdicom latest go: finding github.com/grailbio/go-netdicom/dimse latest go: finding github.com/grailbio/go-dicom v0.0.0 go: github.com/grailbio/go-dicom@v0.0.0: unknown revision v0.0.0 go: error loading module requirements

grailbio / go-netdicom

Can't import module. Problem with go.mod? #5