Description of problem:
On install, I made it all the way to the screen just before installing the 
packages.  Then I wanted to change the grub options (which I had set to
not install grub, since I already had grub installed on the MBR). I hit the
advanced options and set it to install on one of the partitions instead. Then
I hit the back button, and got the anaconda crash. 

Version-Release number of selected component (if applicable):
anaconda-11.1.0.109-1.x86_64.rpm

How reproducible:
Very

Steps to Reproduce:
(what's not listed is just defaults)
1. booted pxe
2. Started http install
3. custom layout
4. Added LV to existing VG *
5. used existing normal partition for /boot (and format) *
6. selected not to install grub
7. select all defaults upto where it will start the package installations
8. hit the back button until you are at the grub screen again
9. select grub
10. select advanced grub options
11. hit next
12. select to install grub on a partition (not MRB)
13. hit back
14. BANG!

* these steps are required for me, but probably isn't the reason for the bug.

  
Actual results:
Anaconda crashes.

Expected results:
Anaconda doesn't crash

Additional info: