Allow ping on closed connection. (Fixes #147)
Allow ping on closed connection. (Fixes #147)

nju520/PyMySQL,PyMySQL/PyMySQL,lzedl/PyMySQL,modulexcite/PyMySQL,PyMySQL/Tornado-MySQL,wraziens/PyMySQL,lzedl/PyMySQL,eibanez/PyMySQL,boneyao/PyMySQL,Geoion/Tornado-MySQL,xjzhou/PyMySQL,methane/PyMySQL,pulsar314/Tornado-MySQL,mosquito/Tornado-MySQL,jheld/PyMySQL,Ting-y/PyMySQL,wraziens/PyMySQL,anson-tang/PyMySQL,eibanez/PyMySQL,jwjohns/PyMySQL,pymysql/pymysql,yeyinzhu3211/PyMySQL,DashaChuk/PyMySQL,NunoEdgarGub1/PyMySQL,MartinThoma/PyMySQL,aio-libs/aiomysql,yeyinzhu3211/PyMySQL,xjzhou/PyMySQL