Roman numeral formatting in LilyPond fret diagrams

[Carl D. Sorensen]

I seem to remember reading on the list that LilyPond is now using some
formatting engine other than the ice-9 formatting engine. Is this correct?

I ask, because in fret diagrams, we format top-frets with roman numerals,
and right now, a fourth fret shows up as "iiii" instead of "iv".

Where should the bug report be sent, or alternatively, where would I find
the formatting code to fix it myself?

Thanks,

Carl