date command no longer handles daylight saving time (summer time) after January 2038

[L. David Baron]

This worked in Ubuntu 17.04 (I *think* -- definitely did work in earlier Ubuntu releases but I'm not 100% sure 17.04 was the last working release) but is broken in Ubuntu 17.10 and in 18.04.

The date command no longer handles summer time (Daylight Saving Time) for dates after January 2038 (i.e., when seconds since the epoch overflows a signed 32-bit time_t).

Steps to reproduce:
 in bash, run the command:
      TZ=America/Los_Angeles date --date=@2196000000

Expected results:
  Wed Aug 3 09:00:00 PDT 2039

Actual results:
  Wed Aug 3 08:00:00 PST 2039

System information:

$ lsb_release -rd
Description: Ubuntu 18.04 LTS
Release: 18.04
$ dpkg -l coreutils | grep "^ii"
ii coreutils 8.28-1ubuntu1 amd64 GNU core utilities
$ dpkg -l tzdata | grep "^ii"
ii tzdata 2018d-1 all time zone and daylight-saving time data
$ uname -sm
Linux x86_64