def robotsrulesetOfDomain(self, domain):
		'''检查domain是否在数据库中,
			否 --> (False, None)
			是 --> (True, 数据库中存储的robots.txt内容)
		'''
		exist = False
		cur = self.conn.cursor()
		# 是否存在
		cur.execute("SELECT 1 FROM Domains WHERE domain=?", (domain,))
		if cur.fetchone() :
			exist = True
		# 存在的话,结果是什么
		cur.execute("SELECT rules FROM Domains,Rulesets "
			"WHERE domain=? AND Domains.did=Rulesets.did"
			,(domain,) )
		ruleset = cur.fetchone()
		return (exist, ruleset)
def get_repository_root(cls, location):
        loc = super(Git, cls).get_repository_root(location)
        if loc:
            return loc
        try:
            r = cls.run_command(
                ['rev-parse', '--show-toplevel'],
                cwd=location,
                show_stdout=False,
                stdout_only=True,
                on_returncode='raise',
                log_failed_cmd=False,
            )
        except BadCommand:
            logger.debug("could not determine if %s is under git control "
                         "because git is not available", location)
            return None
        except InstallationError:
            return None
        return os.path.normpath(r.rstrip('\r\n'))