qemu-img should allow resizing image with snapshots

Currently it's not possible to resize a disk image with qemu-img if image in question has snapshots associated. I'm not entirely sure this is technically possible but if it is, it would be really nice to support that.

$ qemu-img --version
qemu-img version 2.4.1 (qemu-2.4.1-8.fc23), Copyright (c) 2004-2008 Fabrice Bellard

The QEMU project is currently considering to move its bug tracking to
another system. For this we need to know which bugs are still valid
and which could be closed already. Thus we are setting older bugs to
"Incomplete" now.

If you still think this bug report here is valid, then please switch
the state back to "New" within the next 60 days, otherwise this report
will be marked as "Expired". Or please mark it as "Fix Released" if
the problem has been solved with a newer version of QEMU already.

Thank you and sorry for the inconvenience.


Implemented in 7fa140abf69675b7b83af32de.  Note that every internal snapshot has a disk size associated with it, though, so applying a snapshot from when the image had a different size means the image size will be reverted to what it was as the time of the snapshot.