debian: add less as a build dependency For builds that run on hermetic environments, it's possible that the "less" package is not installed by default, yet it's needed for tests to pass after revision bf5e13e38390 (which sets less as the fallback pager).

strip: use the 'writenewbundle' function to get bundle on disk This will ensure the backup bundle use the best available logic (eg: includes relevant caches so that we loose less of them on strip.)

perfphases: add 'perfphases' command This commands benchmark the time spend computing the data in a repository.