R devel - Oct 2018 - Buglet in handling times in R-3.5.1

Here on my Mac it looks worse: not a rounding difference, but an off-by-one
error for fractional seconds before 1970, looks like the conversion to POSIXlt
is doing something wrong:

Options(digits=12)
as.numeric(as.POSIXlt(as.POSIXct('1969-01-01')))
[1] -31539600
# As expected
as.numeric(as.POSIXlt(as.POSIXct('1969-01-01')+.1))
[1] -31539598.9
# An additional second disappears (and no, there was no (negative) leap second)

I'm not enough at home in C to get to the core of it, the problem is in the
.Internal call
Hoping somebody can investigate further.
Specs: R 3.5.1; macOS 10.13.6

Best regards, 
Emil Bode
 

?On 09/10/2018, 17:27, "R-devel on behalf of Russell, George"
<r-devel-bounces at r-project.org on behalf of g.russell at
eos-solutions.com> wrote:

    Dear R developers,
    
    I have found a minute bug in R-3.5.1 (Windows version), about how times not
an exact number of seconds are displayed.
    > as.POSIXct("1969-01-01 01:00")+0.3
    [1] "1969-01-01 01:00:01 CET"
    > as.POSIXct("1970-01-01 01:00")+0.3
    [1] "1970-01-01 01:00:00 CET"
    
    So for 1969, adding 0.3 of a second means you round UP, for 1970 you round
DOWN. But I think it should be consistent.
    
    At the end of this message I have put the usual version information.
    
    Thanks for all your help and for your work on this wonderful product.
    
    
    > R.version
                   _
    platform       x86_64-w64-mingw32
    arch           x86_64
    os             mingw32
    system         x86_64, mingw32
    status
    major          3
    minor          5.1
    year           2018
    month          07
    day            02
    svn rev        74947
    language       R
    version.string R version 3.5.1 (2018-07-02)
    nickname       Feather Spray
    
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