CKAN version
2.9

Describe the bug
When Datastore is enabled and Resouce is uploaded to Datastore, on Resource page Go to resource/Download button become select box, when User clicks on it, file is being downloaded in an appropriate format, but without the file extension (for example "e854b0dc-fc44-4720-a852-e983351304f8", while should be "e854b0dc-fc44-4720-a852-e983351304f8.csv").

Expected behavior
File returned with an appropriate selected format.