Description of problem: Yumex crashes when package not upgradable; not sure of exact condition but will supply example


Version-Release number of selected component (if applicable):
yumex-2.9.6-3.fc13.noarch
yum-utils-1.1.24-2.fc13.noarch
yum-metadata-parser-1.1.4-1.fc13.x86_64
yum-presto-0.6.2-1.fc13.noarch
yum-3.2.25-12.fc13.noarch

How reproducible:
100% of the time on certain errors

Steps to Reproduce:
1. Run yumex
2. select gegl for updating
3. Click Apply 
4. Error msg pops up (see below)
5. Click on Close button to close error window
6. Error window and yumex both go away
  

Expected results:
Error window closes, Yumex stays open ready for another transaction

Additional info:
1. Error msg from yumex:
Error msg - exception was triggered:
Traceback (most recent call last):
  File "/usr/lib/python2.6/site-packages/yumexbackend/yum_server.py", line 1138, in dispatcher
    self.parse_command(args[0], args[1:])
  File "/usr/lib/python2.6/site-packages/yumexbackend/yum_server.py", line 1094, in parse_command
    self.build_transaction()
  File "/usr/lib/python2.6/site-packages/yumexbackend/yum_server.py", line 674, in build_transaction
    rc, msgs = self.buildTransaction()
  File "/usr/lib/python2.6/site-packages/yum/__init__.py", line 815, in buildTransaction
    (rescode, restring) = self.resolveDeps()
  File "/usr/lib/python2.6/site-packages/yum/depsolve.py", line 714, in resolveDeps
    CheckDeps, checkinstalls, checkremoves, missing = self._resolveRequires(errors)
  File "/usr/lib/python2.6/site-packages/yum/depsolve.py", line 816, in _resolveRequires
    (checkdep, missing, errormsgs) = self._processReq(po, dep)
  File "/usr/lib/python2.6/site-packages/yum/depsolve.py", line 285, in _processReq
    CheckDeps, missingdep = self._requiringFromInstalled(po, requirement, errormsgs)
  File "/usr/lib/python2.6/site-packages/yum/depsolve.py", line 419, in _requiringFromInstalled
    return self._requiringFromTransaction(requiringPo, requirement, errorlist)
  File "/usr/lib/python2.6/site-packages/yum/depsolve.py", line 525, in _requiringFromTransaction
    msg = self._err_missing_requires(requiringPo, requirement)
  File "/usr/lib/python2.6/site-packages/yum/depsolve.py", line 313, in _err_missing_requires
    msg = self.dsCallback.format_missing_requires(reqPo, reqTup)
  File "/usr/share/yum-cli/output.py", line 1638, in format_missing_requires
    for pkg in sorted(yb.rpmdb.getProvides(needname)):
AttributeError: 'NoneType' object has no attribute 'rpmdb'


2. Error msg from yum upgrade gegl:
/usr/lib/python2.6/site-packages/yum$ sudo yum upgrade gegl
Loaded plugins: langpacks, presto
Adding en_US to language list
Setting up Upgrade Process
Resolving Dependencies
--> Running transaction check
---> Package gegl.x86_64 0:0.1.0-3.fc13 set to be updated
--> Processing Dependency: libbabl-0.1.so.0()(64bit) for package: gegl-0.1.0-3.fc13.x86_64
--> Running transaction check
--> Processing Dependency: libbabl-0.0.so.0()(64bit) for package: 2:gimp-2.6.8-1.fc13.x86_64
---> Package babl.x86_64 0:0.1.2-1.fc13 set to be updated
--> Finished Dependency Resolution
Error: Package: 2:gimp-2.6.8-1.fc13.x86_64 (@rawhide)
           Requires: libbabl-0.0.so.0()(64bit)
           Removing: babl-0.1.0-5.fc13.x86_64 (installed)
 You could try using --skip-broken to work around the problem
 You could try running: rpm -Va --nofiles --nodigest