Version-Release number of selected component:
dnf-2.0.0-2.fc26

Additional info:
reporter:       libreport-2.9.0
cmdline:        /usr/libexec/system-python /bin/dnf history info last..last-20
executable:     /bin/dnf
kernel:         4.9.0-1.fc26.x86_64
runlevel:       N 5
type:           Python3
uid:            0

Truncated backtrace:
output.py:1508:historyInfoCmd:AttributeError: 'list' object has no attribute 'add'

Traceback (most recent call last):
  File "/bin/dnf", line 58, in <module>
    main.user_main(sys.argv[1:], exit_code=True)
  File "/usr/lib/python3.6/site-packages/dnf/cli/main.py", line 175, in user_main
    errcode = main(args)
  File "/usr/lib/python3.6/site-packages/dnf/cli/main.py", line 61, in main
    return _main(base, args)
  File "/usr/lib/python3.6/site-packages/dnf/cli/main.py", line 99, in _main
    return cli_run(cli, base)
  File "/usr/lib/python3.6/site-packages/dnf/cli/main.py", line 115, in cli_run
    cli.run()
  File "/usr/lib/python3.6/site-packages/dnf/cli/cli.py", line 936, in run
    return self.command.run()
  File "/usr/lib/python3.6/site-packages/dnf/cli/commands/__init__.py", line 926, in run
    ret = self.output.historyInfoCmd(extcmds, self.opts.tid)
  File "/usr/lib/python3.6/site-packages/dnf/cli/output.py", line 1508, in historyInfoCmd
    tids.add(old.tid)
AttributeError: 'list' object has no attribute 'add'

Local variables in innermost frame:
old: <dnf.yum.history.YumHistoryTransaction object at 0x7f9ba0f319b0>
mtids: set()
tids: []
pats: ['last..last-20']
extcmds: []
self: <dnf.cli.output.Output object at 0x7f9ba106f400>