which version to use for a convert-ly rule?

[Andrew Hawryluk]

I've pulled from origin and fixed a bug (don't get too excited - it
may have been the tiniest bug ever):
http://code.google.com/p/lilypond/issues/detail?id=729

I see that the most recent rule is 2.13.0, so my rule should be 2.13.x
where x >= 0. Do I use the current development version or current + 1
and how do I check which version we're up to?

Andrew