I worked around this problem by building a current version of rpm (4.15.1) from source.  I prefixed the build to /usr/local, with the exception of var which I pointed to the system rpm db.  The versions were close enough that I figured there was no major schema difference.  I used the updated rpm command to manually install virt-win, then updated everything else with the normal system rpm.  I thought of upgrading the system to the new version of rpm, looking at the installed rpm's SPEC file, there are many patches over the stock code.  I don't have the time to go through and figure out which patches are minor fixes, and which may make major changes to the way rpm works on RedHat/CentOS.  I decided I didn't want to introduce something that could cause me more problems in the future, especially not for a single package.  I am concerned this type of problem may spread as more people build rpms that use the new compression method.