Converting SPDX 2 to 3 generates incorrect namespace

[goneall]

Converting:

ExternalDocumentRef:DocumentRef-hello-go-src https://swinslow.net/spdx-examples/example6/hello-go-src-v2 SHA1: b3018ddb18802a56b60ad839c98d279687b60bd6

to SPDX 3 generates:

    {
      "type" : "NamespaceMap",
      "prefix" : "DocumentRef-hello-go-src",
      "namespace" : "https://swinslow.net/spdx-examples/example6/hello-go-src-v2"
    }

The namespace should be "https://swinslow.net/spdx-examples/example6/hello-go-src-v2#" with the # appended.