Reasoning behind convert-ly rule for stable update?

[David Kastrup]

Hi,

I've postponed doing the "big" convert-ly update beyond 2.18 version
numbers since it's bad for merge conflict resolution (there are
literally thousands of files affected).

Does anybody know _why_ convert-ly updates at least to the last stable
version number even if nothing else has been changed?

For one thing, it might be a question of efficiency, granted.  Going
through every conversion rule from history's end to today repeatedly is
likely to be expensive.

But for another, it loses significant information.  Is there some way we
can retain this information?  Like adding a comment
% convert-ly version "2.17.28"
or something, and when convert-ly sees this comment, it only deals with
that until it does encounter an actually changing conversion?

Or make \version accept a range?

\version "2.16.0 - 2.17.28"

Then LilyPond just needs to check the first number, and convert-ly just
deals with the second number as long as it does not need to add another
conversion.

-- 
David Kastrup