Fix test error on Python 2.6
Fix test error on Python 2.6

Dufy/wechatpy,jxtech/wechatpy,tdautc19841202/wechatpy,cloverstd/wechatpy,tdautc19841202/wechatpy,messense/wechatpy,zaihui/wechatpy,navcat/wechatpy,mruse/wechatpy,tdautc19841202/wechatpy,Luckyseal/wechatpy,chenjiancan/wechatpy,Luckyseal/wechatpy,navcat/wechatpy,wechatpy/wechatpy,EaseCloud/wechatpy,mruse/wechatpy,Luckyseal/wechatpy,cysnake4713/wechatpy,chenjiancan/wechatpy,zhaoqz/wechatpy,cloverstd/wechatpy,zhaoqz/wechatpy,EaseCloud/wechatpy,Dufy/wechatpy,cysnake4713/wechatpy,zaihui/wechatpy,hunter007/wechatpy,hunter007/wechatpy,cysnake4713/wechatpy