Hi Dave,
Short time after posting this message, the problem stopped for this particular file and I was able to download it fully and unpack it.
After this I have had som 15 retries on http://public-repo-1.hortonworks.com/HDP/centos6/2.x/updates/2.3.0.0/HDP-2.3.0.0-centos6-rpm.tar.gz which was incomplete even if wget on Linux reported it was successfully downloaded.
As I write this response, it seems as if this file now just came down successfully today for the first time and I have indeed had a successful unpacking for the first time.
I have never modified the download commands or unpacking commands, so I have been suspecting the Hortonworks portal for delivering incomplete files all along. Please validate whether this issue is observed by multiple customers.
Best regards,
Eirik Øra, Oslo, Norway