Changelog:
==========
-Fix crash with fresh subprocess, if the build backend is setuptools
automatically enable fresh subprocesses for build backend calls
-Support enabling fresh subprocess for packaging build backends via fresh_subprocess
-Allow plugins attaching additional information to --version via
tox_append_version_info method in the plugin module
Signed-off-by: Wang Mingyu <wangmy@fujitsu.com>
Signed-off-by: Khem Raj <raj.khem@gmail.com>
