Description of problem:
dnf distro-sync doesn't work for packages. This worked in yum and can be handy e.g. during development to return the package to its distro version. One doesn't need to think whether update or downgrade is needed.

Version-Release number of selected component (if applicable):
dnf-0.4.7-1.fc20.noarch

How reproducible:
always

Steps to Reproduce:
1. dnf distro-sync acpid

Actual results:
distro-sync accepts no package specs.

Expected results:
Sync of acpid to its distro version.

Additional info:
This works in yum:
# yum distro-sync acpid
...upgrade or downgrade is performed if needed