revert: add a fullreposet class...
revert: add a fullreposet class
Every revset evaluation starts from `subset = spanset(repo)` and a lot of
revset predicates build a `spansetrepo` for their internal needs.
`spanset` is a generic class that can handle any situation. As a result a lot
of operation between spanset result in an `orderedlazyset`, a safe object but
suboptimal in may situation.
So we introduce a `fullreposet` class where some of the operation will be
overwritten to produce more interesting results.
