[Milhouse]

This would suggest an internet connectivity problem on the device you are running the script. The first error is the version check against github (possibly a DNS failure). As you didn't experience this error a second time, that would suggest the internet connection is intermittent. An inability to download artwork from the internet (when the artwork does appear to exist) would again suggest a flaky internet connection.

Can you confirm the XBMC client has a working internet connection? It might be worth checking the XBMC log for errors too, as it is XBMC that is attempting (and failing) to download the artwork.