Description of problem:
When you run virt-builder to create a new image, and pass the option --install with some packages, dnf breaks with the error:

Traceback (most recent call last):
  File "/bin/dnf", line 35, in <module>
    main.user_main(sys.argv[1:], exit_code=True)
  File "/usr/lib/python3.4/site-packages/dnf/cli/main.py", line 198, in user_main
    errcode = main(args)
  File "/usr/lib/python3.4/site-packages/dnf/cli/main.py", line 84, in main
    return _main(base, args)
  File "/usr/lib/python3.4/site-packages/dnf/cli/main.py", line 144, in _main
    ret = resolving(cli, base)
  File "/usr/lib/python3.4/site-packages/dnf/cli/main.py", line 173, in resolving
    base.do_transaction(display=displays)
  File "/usr/lib/python3.4/site-packages/dnf/cli/cli.py", line 220, in do_transaction
    self.gpgsigcheck(downloadpkgs)
  File "/usr/lib/python3.4/site-packages/dnf/cli/cli.py", line 251, in gpgsigcheck
    if not sys.stdin.isatty() and not ay:
AttributeError: 'NoneType' object has no attribute 'isatty'


Probably trying to see if it should ask for confirmation on the gpg signature or something.


Version-Release number of selected component (if applicable):
$ rpm -qa dnf
dnf-1.1.4-2.fc23.noarch

How reproducible:
Just try to run virt-builder with the --install option, for example:
$ virt-builder -o v1.qcow2 --cache $PWD --format qcow2 --arch x86_64 --install qemu-guest-agent --root-password password:12345 fedora-23

Steps to Reproduce:
1.Just try to run virt-builder with the --install option on fedora-23 os version
2.
3.

Actual results:
Fails to create the image with dnf error

Expected results:
Image created and packages installed

Additional info: