Description of problem:
Hello,
Fresh installation of fedora21 Xfce spin.
The machine just rebooted of first update, i did one packet research with dnf then one with yum and finally did :
[theo@localhost ~]$ su -c 'dnf install firefox'
Then wooops.

Version-Release number of selected component:
dnf-0.6.3-2.fc21

Additional info:
reporter:       libreport-2.3.0
cmdline:        /usr/bin/python -OO /usr/bin/dnf install firefox
dso_list:       python-librepo-1.7.10-1.fc21.x86_64
executable:     /usr/bin/dnf
kernel:         3.17.6-300.fc21.x86_64
runlevel:       N 5
type:           Python
uid:            0

Truncated backtrace:
progress.py:148:end:UnicodeDecodeError: 'ascii' codec can't decode byte 0xc3 in position 177: ordinal not in range(128)

Traceback (most recent call last):
  File "/usr/bin/dnf", line 36, in <module>
    main.user_main(sys.argv[1:], exit_code=True)
  File "/usr/lib/python2.7/site-packages/dnf/cli/main.py", line 182, in user_main
    errcode = main(args)
  File "/usr/lib/python2.7/site-packages/dnf/cli/main.py", line 84, in main
    return _main(base, args)
  File "/usr/lib/python2.7/site-packages/dnf/cli/main.py", line 141, in _main
    ret = resolving(cli, base)
  File "/usr/lib/python2.7/site-packages/dnf/cli/main.py", line 160, in resolving
    base.do_transaction()
  File "/usr/lib/python2.7/site-packages/dnf/cli/cli.py", line 208, in do_transaction
    total_cb)
  File "/usr/lib/python2.7/site-packages/dnf/base.py", line 829, in download_packages
    errors = dnf.repo.download_payloads(payloads, drpm)
  File "/usr/lib/python2.7/site-packages/dnf/repo.py", line 125, in download_payloads
    librepo.download_packages(targets, failfast=True)
  File "/usr/lib64/python2.7/site-packages/librepo/__init__.py", line 1489, in download_packages
    return _librepo.download_packages(list, failfast)
  File "/usr/lib/python2.7/site-packages/dnf/util.py", line 144, in new_func
    name = '%s.%s' % (args[0].__class__.__name__, fn.__name__)
  File "/usr/lib/python2.7/site-packages/dnf/util.py", line 146, in new_func
    return fn(*args, **kwargs)
  File "/usr/lib/python2.7/site-packages/dnf/repo.py", line 315, in _mirrorfail_cb
    self.progress.end(self, dnf.callback.STATUS_MIRROR, err)
  File "/usr/lib/python2.7/site-packages/dnf/cli/progress.py", line 148, in end
    msg = '%s%-*s\n' % (msg, left, err_msg)
UnicodeDecodeError: 'ascii' codec can't decode byte 0xc3 in position 177: ordinal not in range(128)

Local variables in innermost frame:
status: 3
text: u'firefox-34.0-1.fc21.x86_64.rpm'
self: <dnf.cli.progress.MultiFileProgressMeter object at 0x7f5f7aa0a150>
err_msg: 'Curl error: Failure when receiving data from the peer for ftp://ftp.ciril.fr/pub/linux/fedora/linux/updates/21/x86_64/f/firefox-34.0-1.fc21.x86_64.rpm [Recv failure: Connexion r\xc3\xa9-initialis\xc3\xa9e par le correspondant]'
start: 1419124279.216297
left: 100
msg: u'[MIRROR] firefox-34.0-1.fc21.x86_64.rpm: '
now: 1419124279.216297
payload: <dnf.repo.RPMPayload object at 0x7f5f7a9c6f50>
size: 69868724