qemu-img fixed vhd issues
This bug has been copied automatically from: https://bugs.launchpad.net/qemu/+bug/1367365
qemu-img returns fixed vhd images file format to be raw. This happens because only the header is seeked for image signatures when getting the image format. In fact, unlike dynamic vhd images, differencing vhds don't have the footer copied in the header. An easy fix would be to just search the last 512B for the 'conectix' signature. Also, the fixed vhds created by qemu-img seem to be corrupted from Powershell POV.