title: Fatal: Not possible to fast-forward, aborting
body: <p>Why is Git not allowing me to fast forward merge anymore?  If I try to force it using <code>--ff-only</code>, I get the message "fatal: Not possible to fast-forward, aborting."  I realize that there are huge advantages to <code>merge --no-ff</code>, but I'm just puzzled why I can't <code>--ff-only</code> now?</p>