revlog: introduce v2 format As documented in [1], this is still tentative and could be subject to change, but we need to lay down the foundations in order to work on the next abstraction layers. [1] https://www.mercurial-scm.org/wiki/RevlogV2Plan Differential Revision: https://phab.mercurial-scm.org/D9843

formatting: fix redundant parentheses These were introduced by 0d055849d5f9d682ef931d2566b760d5c6bf7e52. Differential Revision: https://phab.mercurial-scm.org/D10229

wsgicgi: switch the default PATH_INFO back to str It looks like everything here is meant to be str, and regressed in 687b865b95ad. Pytype didn't flag this, but is really confused about the range of possible types for the dictionary values, and flagged missing `lower()` on various types in this area. Differential Revision: https://phab.mercurial-scm.org/D10204