Apparently a local texmf tree no longer requires the ls-R file. Since how long, I know not, nor care I particularly. Nor expect I you to care, particularly, but I was tickled by it. Yet another piece of obscurity and complication getting slightly simpler in the LaTeX world.

(Thanks to Micha — I discovered this while helping him tidy up his texmf tree. And yes, I guess this is less down to (La)TeX and more down to my distribution, details jargon technicalities disclaimer.)