manifest: don't go through revlog to access node symbols The revlog module re-exports some node.* symbols courtesy of importing them. Let's access the node.* symbols via our local import. Differential Revision: https://phab.mercurial-scm.org/D4388

manifest: make tree a public attribute changegroup generation accesses this attribute. We should make it public and expose it on the interface. Differential Revision: https://phab.mercurial-scm.org/D4387