When trying to install postgresql:

# yum install postgresql*
Loading "installonlyn" plugin
Setting up Install Process
Parsing package install arguments
Resolving Dependencies
--> Running transaction check
---> Package postgresql-python.i386 0:8.2.3-2.fc7 set to be updated
---> Package postgresql-server.i386 0:8.2.3-2.fc7 set to be updated
---> Package postgresql-libs.i386 0:8.2.3-2.fc7 set to be updated
---> Package postgresql.i386 0:8.2.3-2.fc7 set to be updated
--> Processing Dependency: mx for package: postgresql-python
--> Restarting Dependency Resolution with new changes.
--> Running transaction check
---> Package mx.i386 0:2.0.6-3 set to be updated

Dependencies Resolved

=============================================================================
 Package                 Arch       Version          Repository        Size 
=============================================================================
Installing:
 postgresql              i386       8.2.3-2.fc7      fedora            3.0 M
 postgresql-libs         i386       8.2.3-2.fc7      fedora            195 k
 postgresql-python       i386       8.2.3-2.fc7      fedora             66 k
 postgresql-server       i386       8.2.3-2.fc7      fedora            4.1 M
Installing for dependencies:
 mx                      i386       2.0.6-3          fedora            4.5 M

Transaction Summary
=============================================================================
Install      5 Package(s)         
Update       0 Package(s)         
Remove       0 Package(s)         

Total download size: 12 M
Is this ok [y/N]: y
Downloading Packages:
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 172, in main
    base.doTransaction()
  File "/usr/share/yum-cli/cli.py", line 302, in doTransaction
    problems = self.downloadPkgs(downloadpkgs) 
  File "/usr/lib/python2.5/site-packages/yum/__init__.py", line 798, in downloadPkgs
    remote_pkgs.sort(mediasort)
  File "/usr/lib/python2.5/site-packages/yum/__init__.py", line 747, in mediasort
    a = a.getDiscNum()
  File "/usr/lib/python2.5/site-packages/yum/packages.py", line 485, in getDiscNum
    return int(fragid)
ValueError: invalid literal for int() with base 10: ''