localrepo: add optional validation (defaults to off) for incoming changes
This verifies that all manifests are present for incoming changes,
and all files for those manifests are also present. This is a simple
first-pass, and could be better, but seems like a valuable thing to
have, as I've seen pushes in the past that propagated revlog corruption.
% change the id of the tree root
initializing destination source-hg repository
scanning source...
sorting...
converting...
1 Initial add
0 Changed root
% manifest of tip
644 file