tests/test-issue436

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.

#!/bin/sh

hg init a
cd a
hg -v log -v
hg -v log -v x
true