Original issue was descibed in http://reviews.reviewboard.org/r/3804/
A console window would pop up every time popen is invoked on Windows 7 

Unfortunately, this fix has created a regression on other OSes
https://groups.google.com/forum/?fromgroups=#!topic/reviewboard-dev/hbrKN_p5Rvo

The goal of this update is to prevent Popen shell=true unless Windows 7 and python 2.7.x

Please comment it, do not whenever it is the best place/way to implement such _popen_shell=T/F

this can be merged from https://github.com/nanouck/reviewboard

on windows 7 and python 2.7.3
_popen_shell = True

on windows XP and python 2.7.3
_popen_shell = False