devel/hg-git: update past 0.8.5

Update hg-git to 0.8.5 + recent commits for compatibility with current Mercurial
Attempting to use the previous version of hg-git with current hg results
in an error stating the extension only supports version 3.6 of Mercurial.

While here, add NO_ARCH and adjust python version.

PR: 212714
Submitted by: matthew@reztek.cz
Approved by: maintainer timeout (month+)
MFH: 2017Q1