Description of problem:
I'm doing a PXE/NFS update of my laptop from FC5t2 downloaded today.  It starts
up OK, but after asking the initial questions, finding my FC4 installation and
doing the dependency analysis, it dies with an exception, apparently trying to
create /mnt/sysimage/dev/root.

Version-Release number of selected component (if applicable):
FC5t2 

How reproducible:
Always.

Steps to Reproduce:
1. PXE boot target machine
2. Use NFS as install source
3. Go through screens until "finding package dependencies"
  
Actual results:
Crashes with exception.

Expected results:
Update should start.

Additional info:

If I manually remove /mnt/sysimage/dev/root after anaconda mounts /mnt/sysimage
but before install-proper starts, it seems to work OK.  It gets further at least.

I fixed this yesterday should be in todays rawhide tree.