A working example with -simulate option would be nice.

class HarvestRobot(ConfigParserBot, WikidataBot):
    update_options = {
        'always': True,
        'create': False,
        'exists': '',
        'islink': False,
        'multi': False,
    }

The bot always runs as if -always was provided. The change would be trivial, but it could break e.g. bots via repeated jobs on Toolforge.

Change 805891 had a related patch set uploaded (by Xqt; author: Xqt):

[pywikibot/core@master] [IMPR] Add -confirm option to harvest_template.py

https://gerrit.wikimedia.org/r/805891

Change 805891 merged by jenkins-bot:

[pywikibot/core@master] [IMPR] Add -confirm option to harvest_template.py

https://gerrit.wikimedia.org/r/805891