Description of problem:
Anaconda raises Exception while doing disk partitioning

Version-Release number of selected component (if applicable):
not sure, on rescuecd from Oct 2

How reproducible:
possibly always.... at least 3 times it happened to me

Steps to Reproduce:
1. pre-create partitions on disk using VT/2 shell or whatever method (and create
new filesystems on them)
2. boot installation, until anaconda wants partition setup
3. select custom disk layout
4. delete pre-created partitions
5. try to create a new partition
  
Actual results:
exception, reboot.

Expected results:
normal operation

Additional info:
well, i know its weird to do a pre-partitioned setup, it was a little
experiment, i was playing around with filesystems, wanted to know whether its
possible to create a LUKS/cryptsetup root partition, then i couldn't find out
how, so i gave up and tried to delete part-s and create a normal ext3 one