Basically, you can listen on:

IContentEvents.DeletedContentVersion

 on server side then I guess that you'll have a confusion between "Revert To Published" and "Delete Version" action!

But never mind you can use client side as a "spy agency" to do this.

dojo.require(["dojo/aspect", "epi/dependency"], function(aspect, dependencey) {
    var editingCommands = dependency.resolve("epi.cms.contentEditing.command.Editing");
    aspect.before(editingCommands.revertToPublished, "_execute", function() {
        // TODO: Reverting Content To Published
    });
});

I don't try this code above but I think it's should work.

//Ha Bui