Kalarm messes up time of repeating events when daylight saving time changes

[AlainKnaff]

On change to summer time, repeating events that were entered while winter time was active now fire an hour late.

For example, an event initially scheduled to fire at 11:45 now fires at 12:45

1.
$ lsb_release -rd
Description: Ubuntu 16.04.2 LTS
Release: 16.04

2.
$ apt-cache policy kalarm
kalarm:
  Installed: 4:15.12.3-0ubuntu1
  Candidate: 4:15.12.3-0ubuntu1
  Version table:
 *** 4:15.12.3-0ubuntu1 500
        500 http://be.archive.ubuntu.com/ubuntu xenial/universe amd64 Packages
        100 /var/lib/dpkg/status

3. What I expected to happen:
- Time shown in summary should be 11:45
- Time shown in details (after doubleclicking the event) should be 11:45
- The event should fire at 11:45

4. What happens instead:
- Time shown in summary should be 12:45
- Time shown in details (after doubleclicking the event) in indeed 11:45
- The event fires at 12:45

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.