Description of problem:

The `yum` command suggests to use `dnf-2 migrate` for "transfer transaction metadata from yum to DNF". (Why is it necessary, btw?). After you have installed  package"python-dnf-plugins-extras-migrate", you always get the following error when you try to run `dnf-2 migrate` (or `dnf migrate`):

    ...
    1856 YUMDB records found, 0 migrated, 1856 skipped/preserved
    Migrating groups data...
    Yum command has been deprecated, use dnf instead.
    See 'man dnf' and 'man yum2dnf' for more information.

    Traceback (most recent call last):
      File "/bin/dnf-2", 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 185, 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 134, in _main
        cli.run()
      File "/usr/lib/python2.7/site-packages/dnf/cli/cli.py", line 1077, in run
        return self.command.run(self.base.extcmds)
      File "/usr/lib/python2.7/site-packages/dnf-plugins/migrate.py", line 126, in run
        self.migrate_groups()
      File "/usr/lib/python2.7/site-packages/dnf-plugins/migrate.py", line 250, in migrate_groups
    group_cmd._mark_install(installed)
      File "/usr/lib/python2.7/site-packages/dnf/cli/commands/group.py", line 240, in _mark_install
        dnf.comps.install_or_skip(solver.group_install, res.groups, types)
      File "/usr/lib/python2.7/site-packages/dnf/comps.py", line 86, in install_or_skip
        count += install_fnc(grp, types, None)
    TypeError: unsupported operand type(s) for +=: 'int' and 'TransactionBunch'

Version-Release number of selected component (if applicable):

* Fedora 22
* $  dnf --version
1.0.0
  Installed: dnf-0:1.0.0-1.fc22.noarch at 2015-05-21 18:56
  Built    : Fedora Project at 2015-05-02 13:00

  Installed: rpm-0:4.12.0.1-9.fc22.x86_64 at 2015-05-21 18:56
  Built    : Fedora Project at 2015-04-15 09:21

How reproducible:

Always.

Steps to Reproduce:
1. Run `sudo dnf-2 migrate`

Actual results:

(See Python stack trace above)

Expected results:

No Python errors.

Additional info: