Description of problem:
just opened terminal and ran "yum update"

Version-Release number of selected component:
yum-3.4.3-51.fc18

Additional info:
cmdline:        /usr/bin/python -t /usr/share/yum-cli/completion-helper.py -d 0 -C list updates ''
executable:     /usr/share/yum-cli/completion-helper.py
kernel:         3.8.4-202.fc18.x86_64
uid:            1000

Truncated backtrace:
axelget.py:233:postreposetup_hook:OSError: [Errno 13] Permission denied: '/var/cache/yum/x86_64/18/Dropbox/repomd.xml'

Traceback (most recent call last):
  File "/usr/share/yum-cli/completion-helper.py", line 89, in <module>
    main(sys.argv[1:])
  File "/usr/share/yum-cli/completion-helper.py", line 83, in main
    base.doCommands()
  File "/usr/share/yum-cli/cli.py", line 485, in doCommands
    return self.yum_cli_commands[self.basecmd].doCommand(self, self.basecmd, self.extcmds)
  File "/usr/share/yum-cli/completion-helper.py", line 45, in doCommand
    patterns=[get_pattern(extcmds)])
  File "/usr/lib/python2.7/site-packages/yum/__init__.py", line 2709, in doPackageLists
    for (n,a,e,v,r) in self.up.getUpdatesList():
  File "/usr/lib/python2.7/site-packages/yum/__init__.py", line 1033, in <lambda>
    up = property(fget=lambda self: self._getUpdates(),
  File "/usr/lib/python2.7/site-packages/yum/__init__.py", line 840, in _getUpdates
    self._up = rpmUtils.updates.Updates(self.rpmdb.simplePkgList(), self.pkgSack.simplePkgList())
  File "/usr/lib/python2.7/site-packages/yum/__init__.py", line 1014, in <lambda>
    pkgSack = property(fget=lambda self: self._getSacks(),
  File "/usr/lib/python2.7/site-packages/yum/__init__.py", line 780, in _getSacks
    self.repos.populateSack(which=repos)
  File "/usr/lib/python2.7/site-packages/yum/repos.py", line 313, in populateSack
    self.doSetup()
  File "/usr/lib/python2.7/site-packages/yum/repos.py", line 139, in doSetup
    self.ayum.plugins.run('postreposetup')
  File "/usr/lib/python2.7/site-packages/yum/plugins.py", line 187, in run
    func(conduitcls(self, self.base, conf, **kwargs))
  File "/usr/lib/yum-plugins/axelget.py", line 233, in postreposetup_hook
    os.unlink(localMDFile)
OSError: [Errno 13] Permission denied: '/var/cache/yum/x86_64/18/Dropbox/repomd.xml'

Local variables in innermost frame:
conduit: <yum.plugins.PostRepoSetupPluginConduit instance at 0x1fc1560>
localMDFile: '/var/cache/yum/x86_64/18/Dropbox/repomd.xml'
repos: <yum.repos.RepoStorage instance at 0x1c1f0e0>
mirrors: ['http://linux.dropbox.com/fedora/18/']
need_download_mdFile: True
repo: <yum.yumRepo.YumRepository object at 0x1d747d0>
fastest: 'http://linux.dropbox.com/fedora/18/'
conf: <yum.config.YumConf object at 0x1c74050>