Some (recent) ISO images have started having a zero byte as the first
byte of the MBR boot code embedded in the hard disk image.
When the original Lenovo ISO is booted, nobody has reported any issues,
however when a patched IMG file is created from that, it just hangs
- which does match with having bad bootcode data.
I was unable to reproduce the issue when running the images in qemu,
which is even more confusing.
Since every working image has the same first byte (a "CLI" instruction)
we attempt to repair things by simply changing it back to that byte.
Hamish Coleman