Thanks for the patch! I think the feature is worth it. Currently install does not preserve xattrs and so looses any previous capabilities associated with a file.
In any case, capabilities don't need to be implemented using xattrs, and might not be on tmpfs on Linux for example when support is eventually added there. One tricky thing I noticed with capabilities, is that one needs to do after setting any ownership, which you do correctly in the patch. cheers, Pádraig.
