Downloading image with --progress fails for python3 with,
TypeError: 'IterableWithLength' object is not an iterator. This
is because IterableWithLength class does not implemented python3
compatible __next__ method.
Added __next__ method for python3 compatibility.
Change-Id: Ic2114180fac26e9a60678f06612be733e8671bdb
Closes-Bug: #1671365