Description of problem:
This traceback appeared during dnf distro-sync in the clean up phase. The system
ended up with multiple versions of packages.

Version-Release number of selected component:
dnf-2.0.0-0.rc2.3.fc26

Additional info:
reporter:       libreport-2.9.0
cmdline:        /usr/libexec/system-python /usr/bin/dnf distro-sync
executable:     /usr/bin/dnf
kernel:         4.9.0-0.rc7.git3.1.fc26.x86_64
runlevel:       N 5
type:           Python3
uid:            0

Truncated backtrace:
rpmtrans.py:551:_scriptError:AttributeError: 'NoneType' object has no attribute 'name'

Traceback (most recent call last):
  File "/usr/lib/python3.5/site-packages/dnf/yum/rpmtrans.py", line 427, in callback
    self._scriptError(amount, total, key)
  File "/usr/lib/python3.5/site-packages/dnf/yum/rpmtrans.py", line 551, in _scriptError
    name = pkg.name
AttributeError: 'NoneType' object has no attribute 'name'

Local variables in innermost frame:
amount: 1025
pkg: None
self: <dnf.yum.rpmtrans.RPMTransaction object at 0x7f127a049c88>
_: None
total: 2
key: 'calibre'
scriptlet_name: 'PREUN'