Description of problem: Somme commands do not produce any outputs.

Version-Release number of component: dnf.noarch 2.7.5-11.fc28 @updates-testing

Steps to Reproduce in terminal:
1. 'dnf updateinfo --info --advisory=FEDORA-2018-2ac43f79d8'
2. 'dnf updateinfo --info enhancement spectre-meltdown-checker'
3. 'dnf updateinfo --info security'

Actual results: None of these commands produce any values.
Expected results: Outouts to be produced like 'yum' and 'yum-deprecated' do.

Additional info: Assumed as needed advisory associated to spectre-meltdown-checker component. Since it seems that 'dnf' is not intended to get the advisory –which is 'FEDORA-2018-2ac43f79d8'–, value had to be extracted on Centos and Fedora as output resulting from the respective commands:

'yum updateinfo info all package spectre-meltdown-checker'
'yum-deprecated updateinfo info all package spectre-meltdown-checker'

Output on Fedora:
...
  spectre-meltdown-checker-0.36-1.fc28
===============================================================================
  Update ID : FEDORA-2018-2ac43f79d8
  ...
  Type : enhancement
  ...