virt-sparsify: error: libguestfs error: discard cannot be enabled on this
drive: qemu does not support discard for 'parallels' format files

Since Virtuozzo 7.0.11 discard is officially supported for ploop images and I've mounted them with discard and confirmed this functionality works as expected.  Would it be possible to update libguestfs to be aware of this support so the --inplace flag will work?

https://virtuozzosupport.force.com/s/article/VZA-2019-059

"Native discard support in ploop enabling automatic discard requests on all ext4 filesystems over ploop block devices, except containers running on Virtuozzo Storage."

-- 
Jonathan Wright
KnownHost, LLC
https://www.knownhost.com