Datasets in nested catalogs have empty access_urls

[tdrwenski]

When a catalog has a simple dataset like:

  <dataset name="Test Grid Dataset Services" ID="gridDatasetServices" urlPath="localContent/testData.nc" dataType="Grid"/>

Running the code from the thredds default_viewer.ipynb results in a list of services like:

> list(ds.access_urls)
['OpenDAP',
 'DAP4',
 'HTTPServer',
 'WCS',
 'WMS',
 'NetcdfSubset',
 'CdmRemote',
 'ISO',
 'NCML',
 'UDDC']

However, putting the same dataset not the main catalog, but instead a catalog linked through a catalogRef leads to an empty list ofaccess_urls. I think this may be a Siphon issue not a thredds issue because the services are correctly listed in both cases in the thredds html/xml.

Additional notes:

• same problem exists whether you explicitly add services or use the gridServices like in the example above
• problem does not exist for featureCollections or datasetScans like we mostly have on our thredds servers