running 'scrapy crawl' with more than one spider is not supported

Raise code

    def short_desc(self):
        return "Run a spider"

    def run(self, args, opts):
        if len(args) < 1:
            raise UsageError()
        elif len(args) > 1:
            raise UsageError("running 'scrapy crawl' with more than one spider is not supported")
        spname = args[0]

        crawl_defer = self.crawler_process.crawl(spname, **opts.spargs)

        if getattr(crawl_defer, 'result', None) is not None and issubclass(crawl_defer.result.type, Exception):
            self.exitcode = 1
        else: