[1.3.X] Ensure stdin is a tty before handing it to termios, so as to prevent...

[1.3.X] Ensure stdin is a tty before handing it to termios, so as to prevent prolems when running under IDEs.

Backport of [15911] from trunk.

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.3.X@16029 bcc190cf-cafb-0310-a4f2-bffc1f526a37