Description of problem: Yum Extender fails to initialize while downloading repository metadata


Version-Release number of selected component (if applicable): Installed Packages
Name         : dnf
Version      : 2.0.0
Release      : 2.fc26
Arch         : noarch
Size         : 1.0 M
Source       : dnf-2.0.0-2.fc26.src.rpm
Repo         : @System
From repo    : anaconda
Summary      : Package manager forked from Yum, using libsolv as a dependency
             : resolver
URL          : https://github.com/rpm-software-management/dnf
License      : GPLv2+ and GPLv2 and GPL
Description  : Package manager forked from Yum, using libsolv as a dependency
             : resolver.



How reproducible: initiate DNF/YUM extender


Steps to Reproduce:
1. start yum-extender
2. error while initializing
3.

Actual results:  error codes displayed


Expected results:  initialize and function normally


Additional info:

g-io-error-quark: GDBus.Error:org.freedesktop.DBus.Python.AttributeError: Traceback (most recent call last):
  File "/usr/lib64/python3.6/site-packages/dbus/service.py", line 707, in _message_cb
    retval = candidate_method(self, *args, **keywords)
  File "/usr/lib/python3.6/site-packages/dnfdaemon/server/__init__.py", line 83, in newFunc
    rc = func(*args, **kwargs)
  File "/usr/share/dnfdaemon/dnfdaemon-system", line 207, in SetConfig
    rc = self.set_option(setting, value)
  File "/usr/lib/python3.6/site-packages/dnfdaemon/server/__init__.py", line 680, in set_option
    if hasattr(self.base.conf, option):
  File "/usr/lib/python3.6/site-packages/dnfdaemon/server/__init__.py", line 202, in base
    self._get_base()
  File "/usr/lib/python3.6/site-packages/dnfdaemon/server/__init__.py", line 1054, in _get_base
    self._base.setup_base()
  File "/usr/lib/python3.6/site-packages/dnfdaemon/server/backend.py", line 71, in setup_base
    self._packages = Packages(self)
  File "/usr/lib/python3.6/site-packages/dnfdaemon/server/backend.py", line 273, in __init__
    self._inst_na = self._sack.query().installed().na_dict()
AttributeError: 'Query' object has no attribute 'na_dict'
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