This branch exists for the implementation of Compressed Pristines feature. The relevant issue is filed under bug #908. The feature's design is documented at https://docs.google.com/document/d/1ktIsewfMBMVBxbn-Ng8NwkNwAS_QJ6eC7GOygsbBeEc/edit This branch is being managed as a reintegratable branch, with regular catch-up merges from the trunk. TODO: * create an sqlite db (pristine.db) [STARTED] * insert pristines in pristine.db [] * restore pristines from pristine.db [] * pass pristines via zlib [] * discriminate pristines by size [] * added cp-specific tests [] * add upgrade support code []