setup: read .hg_archival.txt for version info (issue1670) Previously, setup.py was enhanced to identify the Mercurial version from either .hg/ or mercurial/__version__.py. When archives are created using 'hg archive' or via hgweb, neither of those options are available. However, there is a .hg_archival.txt file in the root of the archive that has the information. This patch enhances setup.py to identify the Mercurial version from the .hg_archival.txt file when there is no .hg/ or mercurial/__version__.py available.