Fix Clear Case popen problems on Python 2.7.x.
Fix Clear Case popen problems on Python 2.7.x.

On Windows 7, using Python 2.7.x, Clear Case would pop up a console
window every time popen was invoked. We now change the shell= parameter
depending on whether we're running Windows 7 and Python 2.7.

chipx86/reviewboard,KnowNo/reviewboard,chipx86/reviewboard,brennie/reviewboard,sgallagher/reviewboard,davidt/reviewboard,1tush/reviewboard,bkochendorfer/reviewboard,sgallagher/reviewboard,1tush/reviewboard,chipx86/reviewboard,beol/reviewboard,KnowNo/reviewboard,1tush/reviewboard,1tush/reviewboard,brennie/reviewboard,sgallagher/reviewboard,custode/reviewboard,KnowNo/reviewboard,bkochendorfer/reviewboard,reviewboard/reviewboard,1tush/reviewboard,reviewboard/reviewboard,KnowNo/reviewboard,1tush/reviewboard,custode/reviewboard,bkochendorfer/reviewboard,custode/reviewboard,davidt/reviewboard,bkochendorfer/reviewboard,beol/reviewboard,beol/reviewboard,davidt/reviewboard,1tush/reviewboard,1tush/reviewboard,custode/reviewboard,brennie/reviewboard,chipx86/reviewboard,davidt/reviewboard,reviewboard/reviewboard,brennie/reviewboard,reviewboard/reviewboard,beol/reviewboard,1tush/reviewboard,sgallagher/reviewboard