Generators in Python 3 don't have .next method. It's recommended
to use 'next' builtin instead. As it also present in Python >= 2.6
it should make wic code compatible with both Python 2 and Python 3.
[YOCTO #9412]
(From OE-Core rev: 9b7ab632e47d786dd979262015dbfb1254103f83)
Signed-off-by: Ed Bartosh <ed.bartosh@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>