Additional fix for issue #1249 (Mkdir fails if dir exists) on Windows.
Additional fix for issue #1249 (Mkdir fails if dir exists) on Windows.

andrewyoung1991/scons,andrewyoung1991/scons,timj/scons,timj/scons,timj/scons,timj/scons,andrewyoung1991/scons,andrewyoung1991/scons,andrewyoung1991/scons,timj/scons,andrewyoung1991/scons,timj/scons,andrewyoung1991/scons,timj/scons,andrewyoung1991/scons,timj/scons,andrewyoung1991/scons,timj/scons