Impacted versions:
9.0, 10.0, 11.0 (Maybe 8.0)
I don't know if it is really an expected behaviour for odoo but I like to expose it

Steps to reproduce:

1. Open an ir.cron record and change it to:
 - interval: minutes
 - next execution date: now + 1 minute

2. Open the odoo server log

Note: I'm using workers=3 but I don't know if there is possible to reproduce it without workers.

Current behavior:

You will see for each cron execution the following output
```txt
...
2018-06-01 16:18:33,432 20686 INFO 333561-11-0-42aff9-all odoo.modules.registry: Invalidating all model caches after database signaling.
...
2018-06-01 16:17:21,527 20687 INFO 333561-11-0-42aff9-all odoo.modules.loading: loading 1 modules...
2018-06-01 16:17:21,535 20687 INFO 333561-11-0-42aff9-all odoo.modules.loading: 1 modules loaded in 0.01s, 0 queries
2018-06-01 16:17:21,594 20687 INFO 333561-11-0-42aff9-all odoo.modules.loading: loading 206 modules...
2018-06-01 16:17:21,718 20687 INFO 333561-11-0-42aff9-all odoo.modules.loading: 206 modules loaded in 0.12s, 0 queries
2018-06-01 16:17:21,989 20687 INFO 333561-11-0-42aff9-all odoo.modules.loading: Modules loaded.
```

Expected behavior:
 - Review if the method that run from the cron really requires a invalidate cache and delete all registries.
 - Disable "minutes" for cron interval because all cache are deleted then is not valid use them.

Video/Screenshot link (optional):

 - [![IMAGE ALT TEXT HERE](https://img.youtube.com/vi/Be4FIeQjgjk/0.jpg)](https://youtu.be/Be4FIeQjgjk)
openerp.modules.load_modules(registry._db, force_demo, status, update_module)
                except Exception:
                    _logger.exception('Failed to load registry')
                    del cls.registries[db_name]
                    raise
                
                
                
                init_parent = registry._init_parent
                registry = cls.registries[db_name]
                registry._init_parent.update(init_parent)
                cr = registry.cursor()
                try:
                    registry.do_parent_store(cr)
                    cr.commit()
                finally:
                    cr.close()
        registry.ready = True
        if update_module:
            
            cls.signal_registry_change(db_name)
        return registry
    @classmethod
    def delete(cls, db_name):
        """Delete the registry linked to a given database.  """
        with cls.lock():
            if db_name in cls.registries:
                del cls.registries[db_name]
    @classmethod
    def delete_all(cls):