In the dialog that allows to add/delete/edit user accounts that should be
set up during the installation, when the list of user accounts is _empty_,
selecting "Delete" crashes the installer.

The following is the relevant part of the dump written by Python after the
crash:

Traceback (innermost last):
  File "/usr/bin/anaconda.real", line 438, in ?
    intf.run(todo, test = test)
  File "/var/tmp/anaconda-7.0.1//usr/lib/anaconda/text.py", line 1030, in
run
  File "/var/tmp/anaconda-7.0.1//usr/lib/anaconda/textw/userauth_text.py",
line 213, in __call__
  File "/tmp/lib/python1.5/snack.py", line 87, in current
    return self.key2item[self.w.listboxGetCurrent()]
KeyError: 0

Local variables in innermost frame:
self: <snack.Listbox instance at 823cbd0>

ToDo object:
<truncated>