[Rd] Suggestion: Make _R_CHECK_LENGTH_1_LOGIC2_=warn the default for R 3.6.2

Hi, I'm not sure where we are in getting CRAN packages getting their _R_CHECK_LENGTH_1_LOGIC2_=true bugs fixed (*), but maybe it'd help to make _R_CHECK_LENGTH_1_LOGIC2_=warn the new default in the upcoming R 3.6.2? Warnings of type: $ R --vanilla > Sys.setenv("_R_CHECK_LENGTH_1_LOGIC2_" = "warn"

[Rd] BUG?: A copy of base::`+` (primitive) is not a clone but a "pointer"

$ R --vanilla R version 3.6.1 (2019-07-05) -- "Action of the Toes" Copyright (C) 2019 The R Foundation for Statistical Computing Platform: x86_64-pc-linux-gnu (64-bit) ... > str(base::`+`) function (e1, e2) > plus <- structure(base::`+`, class = "plus") > str(plus) function (e1, e2) - attr(*, "c

[Rd] Inappropriate class(o)[!inherits(o,"AsIs")] in get_all_vars

SVN revision 77401 changes x[isM] <- lapply(x[isM], function(o) `class<-`(o, class(o)[class(o) !=  "AsIs"])) to x[isM] <- lapply(x[isM], function(o) `class<-`(o,  class(o)[!inherits(o,"AsIs")])) in function 'get_all_vars' in src/library/stats/R/models.R in R devel. The change is in