Just today learned something that is useful by experiment. I found that RPMFusion hasn't set up an F21 repository, so I use the rawhide repository. As a result of branching of F21, I started noticing that I had a few fc22 packages that ended up getting installed on my system from RPMFusion and I kept seeing updates for fc22.

Since I am using F21 and I do not want F22 rawhide packages installing on the system at the present, and until the fellows over at RPMFusion separate the F21 from F22 packages in the rawhide repository and create an F21 repository, I did the following to prevent the above issue.

I added the following line to my /etc/yum.conf file:

After doing that I no longer see F22 packages in yum or yumex from the rawhide RPMFusion repositories. (I did not know that it was possible to do something like this with the exclude line but I thought it was cool, in any case, and thought I would share for anyone else who wasn't aware of being able to use wildcards like this in the yum.conf file).