Run the preparation sequence required to start a salt master server.

        If sub-classed, don't **ever** forget to run:

            super(YourSubClass, self).prepare()

def prepare(self):
        '''
        Run the preparation sequence required to start a salt master server.

        If sub-classed, don't **ever** forget to run:

            super(YourSubClass, self).prepare()
        '''
        super(Master, self).prepare()

        try:
            if self.config['verify_env']:
                v_dirs = [
                        self.config['pki_dir'],
                        os.path.join(self.config['pki_dir'], 'minions'),
                        os.path.join(self.config['pki_dir'], 'minions_pre'),
                        os.path.join(self.config['pki_dir'], 'minions_denied'),
                        os.path.join(self.config['pki_dir'],
                                     'minions_autosign'),
                        os.path.join(self.config['pki_dir'],
                                     'minions_rejected'),
                        self.config['cachedir'],
                        os.path.join(self.config['cachedir'], 'jobs'),
                        os.path.join(self.config['cachedir'], 'proc'),
                        self.config['sock_dir'],
                        self.config['token_dir'],
                        self.config['syndic_dir'],
                        self.config['sqlite_queue_dir'],
                    ]
                verify_env(
                    v_dirs,
                    self.config['user'],
                    permissive=self.config['permissive_pki_access'],
                    root_dir=self.config['root_dir'],
                    pki_dir=self.config['pki_dir'],
                )
                # Clear out syndics from cachedir
                for syndic_file in os.listdir(self.config['syndic_dir']):
                    os.remove(os.path.join(self.config['syndic_dir'], syndic_file))
        except OSError as error:
            self.environment_failure(error)

        self.setup_logfile_logger()
        verify_log(self.config)
        self.action_log_info('Setting up')

        # TODO: AIO core is separate from transport
        if not verify_socket(self.config['interface'],
                             self.config['publish_port'],
                             self.config['ret_port']):
            self.shutdown(4, 'The ports are not available to bind')
        self.config['interface'] = ip_bracket(self.config['interface'])
        migrations.migrate_paths(self.config)

        # Late import so logging works correctly
        import salt.master
        self.master = salt.master.Master(self.config)

        self.daemonize_if_required()
        self.set_pidfile()
        salt.utils.process.notify_systemd()