docker: pass proxy arguments to docker process Building in Docker when behind a proxy requires passing the proxy variables. Differential Revision: https://phab.mercurial-scm.org/D190

makefile: build on CentOS 6 with a Python 2.7 Differential Revision: https://phab.mercurial-scm.org/D189

osx: wire up genosxversion script The only version strings that are changed are the ones baked into the .pkg - hg's self-reported version string doesn't change, so users will still see our mostly-pip-compatible version strings. For reference, the part of our versioning setup that's not PEP440 compatible is the RC releases - those should be .rc0 insted of -rc. It's too late to change that for the 4.3 cycle, so I'll worry about fixing that during the 4.4 cycle.

osx: new script for generating OS X package versions If you're shipping prerelease or rc packages using Munki, you'll eventually discover that Munki's version comparison logic is not as good as pip's. In theory we should be able to fix Munki, but it seems entirely reasonable to produce version strings that sort reasonably under these conditions. Since the requried logic not brief, add a new script and some tests of that logic. A followup change will wire this into the Makefile.

tests: update mac packaging test expectations Some more files are included these days.

tests: add support in run-tests.py for an environment variable to stop color I don't like the color output, so this gives me a way to easily never see it while still having pygments on my machine.

setup: fix mistake that prevented Python 3 from being excluded My intent was to only allow Python 3 if the right environment variable is set (for when people want to use `pip install .` on hg locally). This fixes the bug in my previous change. I verified that `python3.6 run-tests.py` still passes the tests that passed before, and that all tests pass on 2.7 (including our virtualenv-using installation test). Differential Revision: https://phab.mercurial-scm.org/D185