Description of problem:
For some reason aria2 does not understand the *_proxy environment variables set in my configuration.

Version-Release number of selected component:
fedup-0.7.3-5.fc17

Additional info:
reporter:       libreport-2.1.7
cmdline:        /usr/bin/python /bin/fedup --verbose --network 19 --reboot
executable:     /bin/fedup
kernel:         3.10.11-100.fc18.x86_64
runlevel:       N 5
type:           Python
uid:            0

Truncated backtrace:
yum-fast-downloader.py:111:downloadQueuedFiles:PluginYumExit: aria2c exited with exit code: 8

Traceback (most recent call last):
  File "/bin/fedup", line 181, in <module>
    main(args)
  File "/bin/fedup", line 126, in main
    pkgs = download_packages(f)
  File "/bin/fedup", line 66, in download_packages
    f.download_packages(updates, callback=output.DownloadCallback())
  File "/usr/lib/python2.7/site-packages/fedup/download.py", line 200, in download_packages
    updates = self._downloadPackages(callback)
  File "/usr/lib/python2.7/site-packages/yum/__init__.py", line 6147, in _downloadPackages
    probs = self.downloadPkgs(dlpkgs)
  File "/usr/lib/python2.7/site-packages/yum/__init__.py", line 2224, in downloadPkgs
    self.plugins.run('predownload', pkglist=pkglist)
  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/yum-fast-downloader.py", line 239, in predownload_hook
    downloadQueuedFiles(inputFileName)
  File "/usr/lib/yum-plugins/yum-fast-downloader.py", line 111, in downloadQueuedFiles
    "{0} exited with exit code: {1}".format(downloader_app, ret))
PluginYumExit: aria2c exited with exit code: 8

Local variables in innermost frame:
args: ['aria2c', '--continue', '--check-certificate=false', '--on-download-complete=/usr/libexec/yum-fast-downloader-finalize', '--server-stat-if=/var/cache/yum/x86_64/19/aria2c_server_stats', '--server-stat-of=/var/cache/yum/x86_64/19/aria2c_server_stats', '--max-concurrent-downloads=10', '--min-split-size=1M', '--max-connection-per-server=5', '--input-file=/var/cache/yum/x86_64/19/aria.input']
inputFileName: '/var/cache/yum/x86_64/19/aria.input'
ret: 8