Description of problem:
Something broke the F8 groupupdate yum checksums.  Can't yum groupupdate Base on
any F8 box.  I tried all the steps google suggest for this error.  This bug has
been reproduced on 3 boxes, one of which ran groupupdate ok just the other day.

Version-Release number of selected component (if applicable):
yum-3.2.7-1.fc8

How reproducible:
always, 3 boxes tested so far

Steps to Reproduce:
1. yum clean all
2. yum groupupdate Base
3.
  
Actual results:
Loading mirror speeds from cached hostfile
comps-f8.xml              100% |=========================| 1.2 MB    00:01     
http://www.muug.mb.ca/pub/fedora/linux/updates/8/i386/repodata/comps-f8.xml:
[Errno -1] Metadata file does not match checksum
Trying other mirror.
comps-f8.xml              100% |=========================| 1.2 MB    00:01     
http://mirrors.reflected.net/fedora/linux/updates/8/i386/repodata/comps-f8.xml:
[Errno -1] Metadata file does not match checksum
Trying other mirror.
comps-f8.xml              100% |=========================| 1.2 MB    00:01     
http://gulus.usherbrooke.ca/pub/distro/fedora/linux/updates/8/i386/repodata/comps-f8.xml:
[Errno -1] Metadata file does not match checksum
Trying other mirror.

Expected results:
yum should update without checksum errors

Additional info:
yum update appears to run fine, it's just the groupupdate that fails.  Tried
with and without yum-fastestmirror.  Tried clearing all proxy caches.  Tried
flushing data/metadata many times.