R 2.5.0 devel try issue in conjuntion with S4 method dispatch

Hi,

after updating R 2.5.0 devel yesterday we today observed many new
unexpected failures in our daily package build and test system runs,
which can be traced to recent changes in the implementation in try()
(as noted in NEWS).

Investigating this new implementation I come across an issue in
conjuntion with using S4 classes and methods. try(expr) does not return an
object with attribute 'try-error' in case of method dispatch failure
in the wrapped expression which to me seems not
quite correct.

Examples to reproduce the observation:

##  using functions all is well:
f <- function(x) { print(x); ret<-try(stop("forced.")); print(ret)}

f(3)
[1] 3
Error in try(stop("forced.")) : forced.
[1] "Error in try(stop(\"forced.\")) : forced.\n"
attr(,"class")
[1] "try-error"

##  using S4 classes and methods
setClass("fooBase",
         representation("VIRTUAL",
                        width      = "numeric",
                        height     = "numeric"),
         prototype(width      = 1024,
                   height     = 1024),
         validity = NULL,
         where    = .GlobalEnv,
         sealed   = TRUE,
         )

if (!isGeneric("plotObject")) {

  setGeneric("plotObject",
             def=function(x, y, ...) {
               value <- standardGeneric("plotObject")
               return(value)
             },
             where=.GlobalEnv,
             useAsDefault=TRUE
             )
}

setClass("foo",
         representation("fooBase"),
         validity = NULL,
         where    = .GlobalEnv,
         sealed   = TRUE)

plotObject.foo <- function(x, y) {
  plot(x,y)
}

setMethod("plotObject", signature=c("foo", "numeric"), plotObject.foo,
where=.GlobalEnv)

fooObject <- new("foo")
##  should fail and return object with attribute 'try-error' set
ret <- try(plotObject(fooObject, character(1)))

Error in as.list(call)[[1]] == "doTryCatch" :
        comparison (1) is possible only for atomic and list types