Yum python error (FC8 yum breaks)

[xcamel]

Anyone else seen this:
===============================================
yum list yum
fedora 100% |=========================| 2.1 kB 00:00
primary.sqlite.bz2 100% |=========================| 4.9 MB 00:07
kde-all 100% |=========================| 951 B 00:00
updates 100% |=========================| 2.3 kB 00:00
Traceback (most recent call last):
File "/usr/bin/yum", line 29, in <module>
yummain.main(sys.argv[1:])
File "/usr/share/yum-cli/yummain.py", line 105, in main
result, resultmsgs = base.doCommands()
File "/usr/share/yum-cli/cli.py", line 278, in doCommands
self._getTs()
File "/usr/lib/python2.5/site-packages/yum/depsolve.py", line 77, in _getTs
self._tsInfo.setDatabases(self.rpmdb, self.pkgSack)
File "/usr/lib/python2.5/site-packages/yum/__init__.py", line 526, in <lambda>
pkgSack = property(fget=lambda self: self._getSacks(),
File "/usr/lib/python2.5/site-packages/yum/__init__.py", line 385, in _getSacks
self._pkgSack.excludeArchs(archlist)
File "/usr/lib/python2.5/site-packages/yum/packageSack.py", line 337, in excludeArchs
sack.excludeArchs(archlist)
File "/usr/lib/python2.5/site-packages/yum/sqlitesack.py", line 812, in excludeArchs
cur = cache.cursor()
AttributeError: 'NoneType' object has no attribute 'cursor'
===============================================
This started after an upgrade from FC7 to FC8 using the full DVD (not live CD)

[scottro]

I had some similar errors, though I don't remember the exact ones. I think that what I did was first do yum -y upgrade yum. Then, I think I upgraded various python programs one by one. Then, I tried again with yum upgrade and got lucky, it just worked. (If not, then the issue was attributable to a particular package, and I did yum install --exclude whatever. I *think* it had something to do with mixing freshrpms and livna. However, I'm pretty sure that at least one of the times it happened, I was able to fix it as I said, by upgrading yum by itself first, then python, then various other python related packages. It was hit or miss, but worked.)