Part of lp.services.librarianserver.librariangc View In Hierarchy
The LibraryFileContent records are left untouched for the code that knows how to delete them and the corresponding files on disk.
This is the second step in a full garbage collection sweep. We determine which LibraryFileAlias entries are not being referenced by other objects in the database and delete them, if they are expired (expiry in the past or NULL).