Comment 10 for bug 1274135

I have been working with the tox upstream to sort this out. Long story short is tox 1.7.0 introduced backward incompat changes to posargs parsing which means we can't just fix it without backward compatibility issues. Current suggestion from hpk is we might use a new substitution variable that gives us the behavior we want (the old behavior) so that they can preserve the new behavior with {posargs}.

You can follow along at:
https://bitbucket.org/hpk42/tox/pull-request/85/fix-command-expansion-and-parsing/diff and https://bitbucket.org/hpk42/tox/issue/150/posargs-configerror