tree 9da43bfc2e25a301c3beb777b46b338caa3fc519
parent ef6c72b46b81870f3b7cba9102477959b6ea3e92
author Feng Xiao <xfxyjwf@gmail.com> 1451428606 -0800
committer Feng Xiao <xfxyjwf@gmail.com> 1451428606 -0800

Require six>=1.9 for Python.

We use six sub-modules that aren't available in old versions. Not specifying
this requirement in the setup will lead to much less readable runtime errors.
It's particuarlly problematic for Mac OSX users because the system comes with
an old six version 1.4.1 by default.

[skip ci]