Add the 'on_retry' callback as an option for Predis\MultiExecContext.
Add the 'on_retry' callback as an option for Predis\MultiExecContext.

gencer/predis,quangnguyen90/predis,vend/predis,johnhelmuth/predis,nrk/predis,lvbaosong/predis,mrkeng/predis,channelgrabber/predis,nguyenthaihan/predis,SwelenFrance/predis,SecureCloud-biz/predis,RedisLabs/predis,moria/predis,stokes3452/predis,protomouse/predis,CloudSide/predis,oswaldderiemaecker/predis,WalterShe/predis,RudyJessop/predis,zhangyancoder/predis,dzung2t/predis,gopalindians/predis,dominics/predis