Problem with yum update on Centos 5.4 32bit

I have a VM running Centos 5.4 (32bit). It's running GForge app server together with PostgreSQL.

I have not run yum update in years on this box.

As a result of very-high CPU usage by PostgresSQL, I ran yum update but got:

# yum update
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
Traceback (most recent call last):
  File "/usr/bin/yum", line 29, in ?
    yummain.user_main(sys.argv[1:], exit_code=True)
  File "/usr/share/yum-cli/yummain.py", line 309, in user_main
    errcode = main(args)
  File "/usr/share/yum-cli/yummain.py", line 178, in main
    result, resultmsgs = base.doCommands()
  File "/usr/share/yum-cli/cli.py", line 345, in doCommands
    self._getTs(needTsRemove)
  File "/usr/lib/python2.4/site-packages/yum/depsolve.py", line 101, in _getTs
    self._getTsInfo(remove_only)
  File "/usr/lib/python2.4/site-packages/yum/depsolve.py", line 112, in _getTsInfo
    pkgSack = self.pkgSack
  File "/usr/lib/python2.4/site-packages/yum/__init__.py", line 661, in <lambda>
    pkgSack = property(fget=lambda self: self._getSacks(),
  File "/usr/lib/python2.4/site-packages/yum/__init__.py", line 501, in _getSacks
    self.repos.populateSack(which=repos)
  File "/usr/lib/python2.4/site-packages/yum/repos.py", line 232, in populateSack
    self.doSetup()
  File "/usr/lib/python2.4/site-packages/yum/repos.py", line 79, in doSetup
    self.ayum.plugins.run('postreposetup')
  File "/usr/lib/python2.4/site-packages/yum/plugins.py", line 179, in run
    func(conduitcls(self, self.base, conf, **kwargs))
  File "/usr/lib/yum-plugins/fastestmirror.py", line 176, in postreposetup_hook
    if downgrade_ftp and _len_non_ftp(repo.urls) == 1:
  File "/usr/lib/python2.4/site-packages/yum/yumRepo.py", line 676, in <lambda>
    urls = property(fget=lambda self: self._geturls(),
  File "/usr/lib/python2.4/site-packages/yum/yumRepo.py", line 673, in _geturls
    self._baseurlSetup()
  File "/usr/lib/python2.4/site-packages/yum/yumRepo.py", line 614, in _baseurlSetup
    mirrorurls.extend(self._getMirrorList())
  File "/usr/lib/python2.4/site-packages/yum/yumRepo.py", line 1622, in _getMirrorList
    fo = urlgrabber.grabber.urlopen(url, proxies=self.proxy_dict)
  File "/usr/lib/python2.4/site-packages/urlgrabber/grabber.py", line 612, in urlopen
    return default_grabber.urlopen(url, **kwargs)
  File "/usr/lib/python2.4/site-packages/urlgrabber/grabber.py", line 891, in urlopen
    return self._retry(opts, retryfunc, url)
  File "/usr/lib/python2.4/site-packages/urlgrabber/grabber.py", line 852, in _retry
    r = apply(func, (opts,) + args, {})
  File "/usr/lib/python2.4/site-packages/urlgrabber/grabber.py", line 890, in retryfunc
    return URLGrabberFileObject(url, filename=None, opts=opts)
  File "/usr/lib/python2.4/site-packages/urlgrabber/grabber.py", line 1008, in __init__
    self._do_open()
  File "/usr/lib/python2.4/site-packages/urlgrabber/grabber.py", line 1091, in _do_open
    fo, hdr = self._make_request(req, opener)
  File "/usr/lib/python2.4/site-packages/urlgrabber/grabber.py", line 1204, in _make_request
    fo = opener.open(req)
  File "/usr/lib/python2.4/urllib2.py", line 358, in open
    response = self._open(req, data)
  File "/usr/lib/python2.4/urllib2.py", line 376, in _open
    '_open', req)
  File "/usr/lib/python2.4/urllib2.py", line 337, in _call_chain
    result = func(*args)
  File "/usr/lib/python2.4/urllib2.py", line 573, in <lambda>
    lambda r, proxy=url, type=type, meth=self.proxy_open: \
  File "/usr/lib/python2.4/urllib2.py", line 580, in proxy_open
    if '@' in host:
TypeError: iterable argument required
[root@server1 ~]#


What's causing the yum update failure?

I can ping other servers in other subnets by name just and I know my proxy server works.

I have exported the relevanted HTTP_PROXY line in /etc/profile.d/proxy.sh