silenttestrunner: add environment variable to make tests noisy again As I've been working on complicated extension code it's been handy to be able to get standard unittest verbose output so I can find crashers more efficiently.

largefiles: update comments to refer to the right overridden method This cleans up leftovers from b228ad1f79d7 (largefiles: override calculateupdates instead of manifestmerge, 2014-03-02).

revlog: cache chain info after calculating it for a rev (issue4452) This dumb cache works surprisingly well: on a repository with typical delta chains ~50k in length, unbundling a linear series of 5000 revisions (changelogs and manifests only) went from 60 seconds to 3.