Error visiting fedora.is

http://www.fedora.is/fedora/releases/test/28_Beta/Modular/armhfp/os/repodata/repomd.xml 404's
http://www.fedora.is/fedora/releases/test/ has 36_Beta and 37_Beta

```
purldb-visitor-1 | INFO:minecode.management.commands.run_visit:Visiting http://www.fedora.is/fedora/releases/test/28_Beta/Modular/armhfp/os/repodata/repomd.xml
purldb-visitor-1 | ERROR:minecode.management.commands.run_visit:Visit error for URI: http://www.fedora.is/fedora/releases/test/28_Beta/Modular/armhfp/os/repodata/repomd.xml
purldb-visitor-1 | Exception Exception("get_http_response: Download failed for 'http://www.fedora.is/fedora/releases/test/28_Beta/Modular/armhfp/os/repodata/repomd.xml' with 404")
purldb-visitor-1 | Traceback (most recent call last):
purldb-visitor-1 | File "/app/minecode/management/commands/run_visit.py", line 255, in visit_uri
purldb-visitor-1 | new_uris_to_visit, visited_data, visit_error = _visit_router.process(uri_to_visit)
purldb-visitor-1 | File "/app/minecode/route.py", line 164, in process
purldb-visitor-1 | return endpoint(string, *args, **kwargs)
purldb-visitor-1 | File "/app/minecode/visitors/repomd_parser.py", line 99, in collect_rpm_packages_from_repomd
purldb-visitor-1 | repomd_xml = download(uri)
purldb-visitor-1 | File "/app/minecode/visitors/repomd_parser.py", line 44, in download
purldb-visitor-1 | content = fetch_http(uri)
purldb-visitor-1 | File "/app/minecode/utils.py", line 214, in fetch_http
purldb-visitor-1 | return get_http_response(uri, timeout).content
purldb-visitor-1 | File "/app/minecode/utils.py", line 236, in get_http_response
purldb-visitor-1 | raise Exception('get_http_response: Download failed for %(uri)r '
purldb-visitor-1 | Exception: get_http_response: Download failed for 'http://www.fedora.is/fedora/releases/test/28_Beta/Modular/armhfp/os/repodata/repomd.xml' with 404

```