Specifying subprocess flags to disable popup of cmd in Windows environment

I am using py2exe with gitpython and wondering if there is a way to specify a flag in gitpython's use of subprocess that disables the popup of cmd in the Windows environment, something like

creationflags=win32process.CREATE_NO_WINDOW

I originally posted my corresponding question here (http://stackoverflow.com/questions/33310791/disable-popup-of-cmd-windows-when-using-gitpython-and-py2exe)