manifest: make treemanifestctx store the repo Same as in the last commit, the old treemanifestctx stored a reference to the revlog. If the inmemory revlog became invalid, the ctx now held an old copy and would be incorrect. To fix this, we need the ctx to go through the manifestlog for each access. This is the same pattern that changectx already uses (it stores the repo, and accesses commit data through self._repo.changelog).