Is there any kind of "lastpresent" in the preferred-content expression? If set, git-annex would see if "git log --follow $path -n 1" (or some configurable -n) was present.
The idea seems to be to match files that have been deleted.
I don't see how that could work; preferred content expressions are always matched against files in the working tree.
Even if it were doable, it would be quite expensive if every preferred content query involved a git log...
What are you trying to achieve with this?
The aim is to be able to have some semi-automatic mode (using "git-annex wanted . (lastpresent)"), where file paths which you "git-annex get" one time always get updated to the latest version.
Or, you could also use some variant of it the other way round (using "git-annex wanted . (notlastpresent)"): all files would be present by default, but paths which you "git-annex drop"ed once wouldn't become present again.