Description of problem: If a Windows guest has bad sectors (eg. if it came from a physical machine) then virt-resize cannot resize it, because the ntfsresize utility will refuse to run unless the --bad-sectors option is specified. We should either detect and add this option automatically (if that is possible) or we should allow the user to specify this option. Version-Release number of selected component (if applicable): libguestfs 1.21 (Suggested by Eric Blake)
Or even find a way to teach windows that there are no longer any bad sectors in the copy (perhaps by clearing or deleting the hidden $BadClust file), since the destination file is not the same block device as the source that had bad clusters in the first place.
Looks like 'ntfsfix --clear-bad-sectors /dev/...' is the way to modify the file system to force windows to quit treating sectors as bad.