Traceback (most recent call first):
  File "/usr/lib/python2.4/site-packages/yum/packages.py", line 612, in tagByName
    raise Errors.MiscError, "Unknown header tag %s" % tag
  File "/usr/lib/python2.4/site-packages/yum/packages.py", line 629, in returnSimple
    return self.tagByName(thing)
  File "/usr/lib/anaconda/sortedtransaction.py", line 17, in __getMedia
    uri = po.returnSimple('basepath')
  File "/usr/lib/anaconda/sortedtransaction.py", line 42, in add
    id = self.__getMedia(txmember.po)
  File "/usr/lib/python2.4/site-packages/yum/transactioninfo.py", line 298, in
addObsoleted
    self.add(txmbr)
  File "/usr/lib/python2.4/site-packages/yum/__init__.py", line 1840, in update
    self.tsInfo.addObsoleted(installed_pkg, obsoleting_pkg)
  File "/usr/lib/anaconda/yuminstall.py", line 960, in doPostSelection
    self.ayum.update()
  File "/usr/lib/anaconda/backend.py", line 154, in doPostSelection
    return anaconda.backend.doPostSelection(anaconda)
  File "/usr/lib/anaconda/dispatch.py", line 200, in moveStep
    rc = stepFunc(self.anaconda)

  File "/usr/lib/anaconda/dispatch.py", line 123, in gotoNext
    self.moveStep()
  File "/usr/lib/anaconda/gui.py", line 919, in nextClicked
    self.anaconda.dispatch.gotoNext()
MiscError: Unknown header tag basepath

Local variables in innermost frame:
self: glibc-kernheaders - 3.0-5.2.x86_64
tag: basepath
e: 'unknown header tag'

Full details...
http://devserv.devel.redhat.com/~wtogami/anacrash/

It seemed to do this on every package that was no longer shipped in FC6.  We
removed each, the tried upgrade again, then it would crash again.  We repeated
this until it crashed on dbus-devel in this same manner... which did not fit
this pattern.