Description of problem:
Problem occured during installation of a package using yumex GUI in Xfce session

1. install Fedora 26 Alpha with Xfce in a virtual machine
2. create local user account with administrative rights
3. after installation and reboot log in with user account
4. start yumex: Applications -- Administration -- Yum Extender (DNF)
5. in tab Packages click on 'All' on the left side
6. activate package 'auter' and install it with 'apply pending actions' button in upper right hand corner

Version-Release number of selected component:
yumex-dnf-4.3.3-4.fc26

Additional info:
reporter:       libreport-2.9.1
cmdline:        /usr/bin/python3 /usr/bin/yumex-dnf
crash_function: on_RPMProgress
exception_type: KeyError
executable:     /usr/bin/yumex-dnf
kernel:         4.11.0-0.rc5.git0.1.fc26.x86_64
runlevel:       N 5
type:           Python3
uid:            1000

Truncated backtrace:
dnf_backend.py:228:on_RPMProgress:KeyError: 'scriptlet'

Traceback (most recent call last):
  File "/usr/lib/python3.6/site-packages/dnfdaemon/client/__init__.py", line 187, in __call__
    return getattr(self.proxy, self.method)(*args)
  File "/usr/lib/python3.6/site-packages/dnfdaemon/client/__init__.py", line 228, in _on_g_signal
    self.handle_dbus_signals(proxy, sender, signal, args)
  File "/usr/lib/python3.6/site-packages/dnfdaemon/client/__init__.py", line 556, in handle_dbus_signals
    self.on_RPMProgress(*args)
  File "/usr/lib/python3.6/site-packages/yumex/dnf_backend.py", line 228, in on_RPMProgress
    self.frontend.infobar.info_sub(const.RPM_ACTIONS[action] % name)
KeyError: 'scriptlet'

Local variables in innermost frame:
name: 'auter-0.9-1.fc26.noarch (updates-testing)'
num: ' ( 1/1 )'
ts_total: 1
ts_current: 1
te_total: 100
te_current: 100
action: 'scriptlet'
package: 'auter,0,0.9,1.fc26,noarch,updates-testing'
self: <yumex.dnf_backend.DnfRootBackend object at 0x7f137003ad68>