Incorrect leap year at 0200-02-29 in udunits

I found this through the R package units and it causes odd behavior in dates prior to 0200-02-28

library(units)
#> udunits system database from C:/R/Library/3.5/RNetCDF/udunits
x1 <- as_units(1, "seconds since 200-02-28 00:00:00 +00:00")
units(x1) = units:::symbolic_unit("seconds since 1970-01-01 00:00:00 +00:00")
as.POSIXct.numeric(as.numeric(x1), tz = "UTC", origin = as.POSIXct("1970-01-01 00:00:00", 
                                                                   tz = "UTC"))
#> [1] "0200-02-27 00:00:01 UTC"

x2 <- as_units(1, "seconds since 200-03-01 00:00:00 +00:00")
units(x2) = units:::symbolic_unit("seconds since 1970-01-01 00:00:00 +00:00")
as.POSIXct.numeric(as.numeric(x2), tz = "UTC", origin = as.POSIXct("1970-01-01 00:00:00", 
                                                                   tz = "UTC"))
#> [1] "0200-03-01 00:00:01 UTC"

# units thinks there's a leap day there
(as.numeric(x1) - as.numeric(x2))/86400
#> [1] -2

# R does not think there's a leap day there
as.Date("0200-02-29")
#> Error in charToDate(x): character string is not in a standard unambiguous format

^{Created on 2019-03-02 by the reprex package (v0.2.1.9000)}

I came across this problem in real life when using stars::read_ncdf on this file which stores dates with "0000-01-01" as the origin:

mrso_Lmon_FGOALS-g2_historical_r2i1p1_200001-200912.zip

The above code is inside as.POSIXct.units.

https://calendarhome.com/calculate/days-between-2-dates agrees with R and not units.

Unidata / UDUNITS-2

Incorrect leap year at 0200-02-29 in udunits #83