DownloadStream.Skip() does not seem to skip correctly when iterating over multiple chunks. The test cases here identify two cases:

https://play.golang.org/p/z7RDRqU01ZA

1. Skipping less than chunk size if the buffer offset is 0 results in a no-op.
2. When skipping results in the buffer offset being divisible by the chunk size on the last loop iteration in Skip, it resets the offset but does not fill the next buffer.