Dear Maintainer,

Blast from the past, mvo wrote in 2012 a patch to allow apt-ftparchive
generate command to perform Contents update only, however that patch
does not seem to have been applied yet. [1] [2]

I've now rebased it, and tested it to make sure it does provide a
speed-up gain for generating Contents on large repositories, without the
penalty of re-generating dists.

Please consider applying that patch, see attachment.