build: fake PEP440 versions If the current version is not exactly a tag, use a local version specifier to fix it up. PEP 440 uses the "+" separator and only allows alphanumeric and dot, so use dot for further separations. Old devel build: 5.7+155-a163cc36d06b New devel build: 5.7+hg155.a163cc36d06b Differential Revision: https://phab.mercurial-scm.org/D9955