epel-release: consider adding %epel macro ?

[Rex Dieter]

I'd like to be able to conditionalize some package features depending on if 
epel repo is enabled or not.  One way to accomplish that goal is if epel-
release defined some macro, say, something like %{epel}, similar to 
%{feodra} or %{rhel}

(I don't care what the macro is named, as long as the bikeshed remains blue)

My primary motivation is to simplify the task of doing something like:
https://copr.fedoraproject.org/coprs/rdieter/kde4/
where I currently end up patching various .spec files (mostly to enable 
features due to having epel available), and I'd like to be able to minimize 
having to do that.

thoughts?

-- Rex