casper-snapshots and whiteout files

I understand that casper-snapshot is an experimental feature, but the concept has a lot of merit for my use case, so I am trying to tweak its behavior using some add-on scripts.

My question is if anybody knows the reason the '*.wh.*' files are automatically excluded from the compressed snapshots (casper-sn.squashfs, casper-sn.cpio.gz), and are kept in the non-compressed snapshots (casper-sn.ext2).

As I understand it, those are aufs whiteout files, used to mask items deleted from the underlying ro filesystem and for other aufs metadata, so it should be useful to conserve them in snapshots. Am I missing something (if so, please point me in the right direction), or is it some legacy leftover from some canceled development attempt?

It seems that this was also reported as a bug (#384073) in 2009, but never addressed.