xbmc/xbmc-packaging — comment on commit 4cc2deae88fae620b3dfe018fa2c0d676affd547
File:  line 0
By amejia1:

@sitzm This should be fine since the older libnfs will have a soname major version of 0, so the library installed would be libnfs0.

I think you have to remove libnfs entirely from launchpad first, than add the lower version back in.