I am installing Google App Engine under Windows (not using Cygwin). After running the bat script, I closed and reopened the cmd.exe and entered inside the
cmd.exe
None of the above helped on Windows 8.1 64 bit. Because the SDK is 32 bit and it installs 64 bit Python.
I solved this by uninstalling the SDK and Python, removing folders. I downloaded python 32 bit, installed it and then the SDK and it worked.