add_period_to_date/add_months returns NA for some dates/periods

[mwmclean]

library(lubridate)
start <- c("2016-04-29 12:00:00 GMT", "2013-10-31 12:00:00 GMT", "2012-05-31 12:00:00 GMT", "2010-06-29 12:00:00 GMT",
           "2014-12-31 12:00:00 GMT", "2015-08-31 12:00:00 GMT", "2013-03-29 12:00:00 GMT", "2014-07-31 12:00:00 GMT")
end <- c("2017-03-25", "2014-03-16", "2012-12-15", "2011-03-25", "2015-10-16" ,"2016-03-16", "2014-03-28" ,"2015-07-22")
mt <- as.POSIXlt(start)
int <- interval(start, end)
id <- int %/% months(1)

int %% months(1)
## [1] NA--NA NA--NA NA--NA NA--NA NA--NA NA--NA NA--NA NA--NA
mt + months(id)
## [1] NA NA NA NA NA NA NA NA
lubridate:::add_months(mt, id)
## [1] NA NA NA NA NA NA NA NA

[vspinu]

I am fixing %% issue as I think it would make more sense to use m+ arithmetic there but others behave as expected. See the docs for %m+%.

With the github version you should see:

> int %% months(1)
[1] 2017-02-28 12:00:00 CET--2017-03-25 CET  
[2] 2014-02-28 12:00:00 CET--2014-03-16 CET  
[3] 2012-11-30 12:00:00 CET--2012-12-15 CET  
[4] 2011-02-28 12:00:00 CET--2011-03-25 CET  
[5] 2015-09-30 12:00:00 CEST--2015-10-16 CEST
[6] 2016-02-29 12:00:00 CET--2016-03-16 CET  
[7] 2014-02-28 12:00:00 CET--2014-03-28 CET  
[8] 2015-06-30 12:00:00 CEST--2015-07-22 CEST
> mt + months(id)
[1] NA NA NA NA NA NA NA NA
> mt %m+% months(id)
[1] "2017-02-28 12:00:00 UTC" "2014-02-28 12:00:00 UTC"
[3] "2012-11-30 12:00:00 UTC" "2011-02-28 12:00:00 UTC"
[5] "2015-09-30 12:00:00 UTC" "2016-02-29 12:00:00 UTC"
[7] "2014-02-28 12:00:00 UTC" "2015-06-30 12:00:00 UTC"
> add_with_rollback(mt, months(id))
[1] "2017-02-28 12:00:00 UTC" "2014-02-28 12:00:00 UTC"
[3] "2012-11-30 12:00:00 UTC" "2011-02-28 12:00:00 UTC"
[5] "2015-09-30 12:00:00 UTC" "2016-02-29 12:00:00 UTC"
[7] "2014-02-28 12:00:00 UTC" "2015-06-30 12:00:00 UTC"
> add_with_rollback(mt, months(id), T, F)
[1] "2017-03-01 UTC" "2014-03-01 UTC" "2012-12-01 UTC" "2011-03-01 UTC"
[5] "2015-10-01 UTC" "2016-03-01 UTC" "2014-03-01 UTC" "2015-07-01 UTC"