Fix background runserver for 1.3<=Django<1.3.7

For early 1.3 Django releases, backgrounded manage.py runserver without
--noreload gets an unhandled exception due to loader thread calling
ensure_echo_on which gets "Inappropriate ioctl for device." Thanks Jiaaro:
http://stackoverflow.com/questions/6369054/run-python-manage-py#6374707