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)
with registry.cursor() as cr:
        openerp.tools.convert_yaml_import(cr, 'base', file(test_file), 'test', {}, 'init')
        if config['test_commit']:
            _logger.info('test %s has been commited', test_file)
            cr.commit()
        else:
            _logger.info('test %s has been rollbacked', test_file)
            cr.rollback()
def load_test_file_py(registry, test_file):
    
    test_path, _ = os.path.splitext(os.path.abspath(test_file))
    for mod_name, mod_mod in sys.modules.items():
        if mod_mod:
            mod_path, _ = os.path.splitext(getattr(mod_mod, '__file__', ''))
            if test_path == mod_path:
                suite = unittest.TestSuite()
                for t in unittest.TestLoader().loadTestsFromModule(mod_mod):
                    suite.addTest(t)
                _logger.log(logging.INFO, 'running tests %s.', mod_mod.__name__)
                stream = openerp.modules.module.TestStream()
                result = unittest.TextTestRunner(verbosity=2, stream=stream).run(suite)
                success = result.wasSuccessful()
                if hasattr(registry._assertion_report,'report_result'):
                    registry._assertion_report.report_result(success)
                if not success:
                    _logger.error('%s: at least one error occurred in a test', test_file)
def preload_registries(dbnames):