[[s]] <- V now consistently gives list() -- fixes dimnames(.)[[1]] <- "A"
The change in itself had been discussed somewhat on the R-devel
mailing list before it happened,
starting here:
https://stat.ethz.ch/pipermail/r-devel/2020-February/079049.html
and also a bit afterwards:
https://stat.ethz.ch/pipermail/r-devel/2020-February/079061.html