Add a test for a bug report from Andreas Nowack.

When there are no packages to install or remove, but new versions must
be installed, the component was doing nothing.
Ensure Yum always synchronizes with the remote distributions.

This ensures that operations that involve only version changes will
get executed, and the system will always be updated.
Merge pull request #17 from piojo/spma-andreas

Make yum run inconditionally