localrepo: make it clear that changegroupsubset doesn't take bases but roots...
localrepo: make it clear that changegroupsubset doesn't take bases but roots
changegroupsubset will take the parents of the roots to find the bases.
Other parts of Mercurial do not expect that, and a result of that is that some
bundles contain more changesets than necessary.
No real changes here - just renaming a parameter to document what it is.