rust: Keep lazily-initialized Changelog and Manifest log on the Repo object
That way if one of them is accessed multiple times it won’t be reopened
from the filesystem.
Differential Revision: https://phab.mercurial-scm.org/D11406
This directory is meant to cache artifacts useful for tests (such as bundle).
Those artifacts need to be cached because they are slow to regenerate on each
test but too large to be tracked within the repository. They are not expected
to change between each run and can be cached.
The `./scripts/` contains code to generate the artifact while the `cache`
directory contains resulting artifact.