I guess this is all due to EOS gateway, we can attack the root cause via handling /files/... URIs.
Just to see if it works better.
Example:http://opendata.cern.ch/eos/opendata/cms/Run2010B/BTau/AOD/Apr21ReReco-v1/file-indexes/CMS_Run2010B_BTau_AOD_Apr21ReReco-v1_0000_file_index.json
is also available as:
http://opendata.cern.ch/record/1/files/CMS_Run2010B_BTau_AOD_Apr21ReReco-v1_0000_file_index.json
From MM chat: