loader: pywatchman appears to already be py3 compatible Our loader was doing some confusing things in pywatchman, but it looks like we shouldn't be using it there anyway.

py3: update test expectations for py3-commands test

context: do not cache manifestctx This will make sure when ctx.repo.manifestlog changes, a correct new manifestctx is returned. repo.manifestlog takes care of caching so the manifestctx won't be reconstructed every time.