Description of problem:

(Reported by shawnjgoff on IRC)

If you do something like:

  virt-sparsify infile /dev/vg/lv

then virt-sparsify will overwrite /dev/vg/lv with a file, which
is not exactly as intended.

It should detect if the output is a block device and (probably)
reject the attempt, although there is a possible use case which
is writing a qcow2 file into an LV (as used by oVirt).

Version-Release number of selected component (if applicable):

virt-sparsify 1.20.11rhel=6,release=2.el6