Fix for issue #391.
Fix for issue #391.

Use a simple protocol between clientsCron() and helper functions to
understand if the client is still valind and clientsCron() should
continue processing or if the client was freed and we should continue
with the next one.

xuguruogu/redis,linfangrong/redis,machicao2013/redis-source-annotated,j0hnma/hszredis,onlymellb/redis-3.0-annotated,hawkchch/redis,pcarrier/redis,yossigo/redis,AplayER/redis,HunanTV/redis,MOON-CLJ/redis,moonbingbing/redis-3.0-annotated,jacklee0810/redis-3.0-annotated,timothyohare/3rdPartySrc-redis,j0hnma/szredis,spearhead-ea/redis,seppo0010/redis,OmarQunsul/graph-redis,seandsky/redis,Hailei/redis,soveran/redis,huangz1990/experiment-redis,iandyh/redis,zy416548283/redis-3.0-annotated,zczhuohuo/redis,guker/redis,pmem/redis,ReadCode/redis-3.0-annotated,figoxu/annotated_redis_source,xujunhai1991/redis,a-pavlov/redis,healerkx/redis,huangz1990/annotated_redis_source,clamoriniere1A/redis,july2993/redis,ErikDubbelboer/redis,j0hnma/hszredis,linfangrong/redis,janekmi/redis,davidradunz/redis,linfangrong/redis,charsyam/redis,huyuezheng/redis,mengyou0304/redis,atreeyang/redis,HouKangkang/redis-3.0-annotated,yossigo/redis,HouKangkang/redis-3.0-annotated,cnbin/redis,splitice/redis,huangz1990/experiment-redis,dramenk/annotated_redis_source,huangz1990/annotated_redis_source,CodeJuan/redis,cloudrain21/redis,MasahikoSawada/redis,josephholsten/redis,duanx/redis,atreeyang/redis,louisliangjun/redis,idning/redis,LongXQ/redis,brg-liuwei/redis,zhcy/redis,cloudrain21/redis,wujf/redis,PradheepShrinivasan/redis,mcanthony/redis,ttuna/msot-redis,wangyikai/redis,josiahcarlson/redis,kmiku7/redis,spearhead-ea/redis,ksarch-saas/redis,magastzheng/redis-3.0-annotated,guker/redis,seandsky/redis,YongMan/redis,zooniverse/redis,dreamquster/redis,netroby/redis,elkingtonmcb/redis,supasate/redis,CodeJuan/redis,universsky/redis,xuzhezhaozhao/redis_reading,rogerchina/redis,weizijun/redis,vincent-vivian-liu/redis,viongpanzi/annotated_redis_source,miaoyc1989/redis-3.0-annotated,ton31337/redis,zhoudayang/redis,seppo0010/rlite-server,neomantra/redis,twskipper/redis,wangyikai/redis,soloestoy/redis,mingyaaaa/redis,badboy/redis,neomantra/redis,thomasdarimont/redis,aluzzardi/redis,hawkchch/redis,soloestoy/redis,SummonY/redis,thomasdarimont/redis,oranagra/redis,izhoujie/redis,haima-zju/redis-3.0-annotated,ncopa/redis,MSOpenTech/redis,h0x91b/redis,OmarQunsul/graph-redis,j0hnma/szredis,louisliangjun/redis,ton31337/redis,colstrom/redis,HunanTV/redis,pietern/redis,zczhuohuo/redis,zy416548283/redis-3.0-annotated,rrsean/redis-3.0-annotated,zguangyu/redis,itamarhaber/redis,cusspvz/redis,MSOpenTech/redis,iandyh/redis,elkingtonmcb/redis,ttuna/msot-redis,netroby/redis,yybirdcf/learn-redis,hedisdb/hedis,Aliceljm1/redis-3.0-annotated,citusdata/redis,slfs007/mk-redis,shshlzh/redis-3.0-annotated,honestme/redis,mumingv/redis,dreamquster/redis,a-pavlov/redis,jingjidejuren/redis,pedigree/redis,healerkx/redis,a-pavlov/redis,raphaelfruneaux/redis,gilala/redis,kaushik94/redis,pkdevbox/redis,SyntaxStacks/redis,zguangyu/redis,SummonY/redis,mengzhejin/RedisStudy,pcarrier/redis,ytjiang/redis,yybirdcf/learn-redis,HeartSaVioR/redis,NBSW/redis,danny200309/annotated_redis_source,ksarch-saas/redis,soveran/redis,shshlzh/redis-3.0-annotated,zooniverse/redis,tjschuck/redis,linfangrong/redis,PKRoma/redis,xlzhan/redis,mgk/redis,mumingv/redis,clamoriniere1A/redis,Aaron1992/redis,mrb/redis,seppo0010/redis,seppo0010/rlite-server,fengshao0907/redis,mattsta/redis,zooniverse/redis,kaushik94/redis,dongqifan2/redis-3.0-annotated,gilala/bjredis,july2993/redis,YuanZhewei/redis,gilala/hbjredis,unasm/redis-3.0-annotated,thomasdarimont/redis,tanghaodong25/redis,PradheepShrinivasan/redis,zhiliaoniu/redis,figoxu/annotated_redis_source,mrb/redis,mgk/redis,CodeJuan/redis,jermnelson/redis,h0x91b/redis,antirez/redis,taoguan/redis,simplestbest/redis,wbailey5/redis,SyntaxStacks/redis,jasonkying/redis,fankeke/redis-3.0-annotated,PradheepShrinivasan/redis,wujf/redis,tzq668766/redis-3.0-annotated,WorkingOfTimtohyZhang/redis-3.0-annotated,mpalmer/redis,ramonsnir/redis,sunheehnus/redis,duanx/redis,gilala/bjredis,xuguruogu/redis,wuxiaowei907/annotated_redis_source,tellapart/redis,jasonkying/redis,pietern/redis,tjschuck/redis,idning/redis,valdsJohn/redis,0x20h/redis,machicao2013/redis-source-annotated,qiyang0221/redis,ctripcorp/redis,0x55/redis-3.0-annotated,Sciumo/redis,honestme/redis,seppo0010/rlite-server,guker/redis,0x55/redis-3.0-annotated,gongice/redis-3.0-annotated,JoeWoo/redis,raphaelfruneaux/redis,wuxiaowei907/annotated_redis_source,Cisphyx/redis-websockets,yossigo/redis,rogerchina/redis,mingyaaaa/redis,haima-zju/redis-3.0-annotated,zhaobo1023/redis-3.0-annotated,rrsean/redis-3.0-annotated,hornen/redis,ipmobiletech/redis,ttuna/msot-redis,ChanningDuan/annotated_redis_source,spinlock/redis,nnog/redis,JoeWoo/redis,WorkingOfTimtohyZhang/redis-3.0-annotated,takeshineshiro/redis,programmecat/redis,sunheehnus/redis,jbochi/parallel_redis,ReadCode/redis-3.0-annotated,fengshao0907/redis,xujunhai1991/redis,zhoudayang/redis,kensou97/redis,saisai/redis,CodeJuan/redis,july2993/redis,shreesundara/redis,timothyohare/3rdPartySrc-redis,dongqifan2/redis-3.0-annotated,cnbin/redis,fengshao0907/redis-3.0-annotated,itamarhaber/redis,xuzhezhaozhao/redis_reading,wprice/redis,nnog/redis,citusdata/redis,rogerlz/redis,mgk/redis,j0hnma/szredis,flashbuckets/redis,gilala/hredis,MOON-CLJ/redis,nuxeh/redis,zhoudayang/redis,darksideofthemoo/redis-histogram,hhli/redis,unasm/redis-3.0-annotated,WorkingOfTimtohyZhang/redis-3.0-annotated,YuanZhewei/redis,nnog/redis,gechong/redis-3.0-annotated,magastzheng/redis-3.0-annotated,ipmobiletech/redis,MSOpenTech/redis,colstrom/redis,RepmujNetsik/redis,YuraLukashik/redis,huangz1990/experiment-redis,flashbuckets/redis,huyuezheng/redis,josiahcarlson/redis,fengshao0907/annotated_redis_source,iandyh/redis,danny200309/annotated_redis_source,vincent-vivian-liu/redis,jbochi/parallel_redis,pkdevbox/redis,4396/redis,aim-for-better/redis,Soledad89/redis,sunheehnus/redis,csuhawk/redis,badboy/redis,Hailei/redis,Instagram/redis,msn217/redis-3.0-annotated,ksarch-saas/redis,spinlock/redis,francischan714/redis,antirez/redis,soloestoy/redis,zczhuohuo/redis,csuhawk/redis,qiyang0221/redis,ChaosCoo/annotated_redis_source,RepmujNetsik/redis,ouyangkongtong/redis,PKRoma/redis,jbochi/redis,onlymellb/redis-3.0-annotated,wangyikai/redis,kensou97/redis,MOON-CLJ/redis,gongice/redis-3.0-annotated,slfs007/mk-redis,HeartSaVioR/redis,zhaobo1023/redis-3.0-annotated,kensou97/redis,SyntaxStacks/redis,wbailey5/redis,davidradunz/redis,rouzier/redis,mcanthony/redis,iandyh/redis,oranagra/redis,pcarrier/redis,harrisonfeng/redis,dayuoba/redis,seppo0010/redis,ofirluzon/redis,ytjiang/redis,holstvoogd/redis,honestme/redis,himoca/redis,gilala/bjredis,saisai/redis,ofirluzon/redis,figoxu/annotated_redis_source,ton31337/redis,drinkthere/redis-3.0-annotated,ErikDubbelboer/redis,moonbingbing/redis-3.0-annotated,charsyam/redis,HunanTV/redis,wenxueliu/redis_comment,hedisdb/hedis,xujunhai1991/redis,tanghaodong25/redis,tzq668766/redis-3.0-annotated,NBSW/redis,jxwr/redis,atreeyang/redis,zczhuohuo/redis,alenslan/redis,yuhc/redis-benchmark-enhanced,idning/redis,josephholsten/redis,spearhead-ea/redis,elkingtonmcb/redis,idning/redis,buobao/redis-3.0-annotated,itugs/redis,shreesundara/redis,zhcy/redis,whille/redis-3.0-annotated,Aliceljm1/redis,0x20h/redis,ctripcorp/redis,wprice/redis,hornen/redis,modulexcite/redis,oranagra/redis,HeartSaVioR/redis,flashbuckets/redis,ytjiang/redis,cusspvz/redis,wbailey5/redis,yuzhangjob/redis-3.0-annotated-unstable,viongpanzi/annotated_redis_source,gaoxianglong/redis,healerkx/redis,Instagram/redis,louisliangjun/redis,Soledad89/redis,AplayER/redis,z-fork/redis,raphaelfruneaux/redis,maodeyi/redis_lua,arijitvt/redis,universsky/redis,josiahcarlson/redis,aluzzardi/redis,AALEKH/redis,ctripcorp/redis,maodeyi/redis_lua,clamoriniere1A/redis,vincent-vivian-liu/redis,nilyang/redis-tdd-annotation,gilala/hredis,kmiku7/redis,sunlianqiang/redis-3.0-annotated,0x20h/redis,Cisphyx/redis-websockets,francischan714/redis,GrimDerp/redis,shining-yang/redis,ytjiang/redis,xuzhezhaozhao/redis_reading,ketor/redis,hawkchch/redis,zy416548283/redis-3.0-annotated,AplayER/redis,brg-liuwei/redis,wujf/redis,SummonY/redis,kensou97/redis,jacklee0810/annotated_redis_source,Soledad89/redis,MSOpenTech/redis,nuxeh/redis,fankeke/redis-3.0-annotated,0x55/redis-3.0-annotated,zguangyu/redis,holstvoogd/redis,GitHubMota/redis,AplayER/redis,cloudrain21/redis,YuraLukashik/redis,dreamquster/redis,rogerlz/redis,jackyan/redis,jingjidejuren/redis,mpalmer/redis,mverrilli/redis,riyan8250/redis,dreamquster/redis,jingjidejuren/redis,Cisphyx/redis-websockets,jacklee0810/annotated_redis_source,csuhawk/redis,msn217/redis-3.0-annotated,thomasdarimont/redis,ChanningDuan/annotated_redis_source,tidatida/annotated_redis_source,mverrilli/redis,riyan8250/redis,takeshineshiro/redis,SummonY/redis,drinkthere/redis-3.0-annotated,wenxueliu/redis_comment,simplestbest/redis,Instagram/redis,YongMan/redis,pmem/redis,ksarch-saas/redis,jasonkying/redis,jermnelson/redis,hgl888/redis,jbochi/redis,huangz1990/experiment-redis,izhoujie/redis,rouzier/redis,abhiklodh/redis,narma/redis,pedigree/redis,h0x91b/redis,mattsta/redis,kmiku7/redis,hhli/redis,gechong/redis-3.0-annotated,Wangyao14cyy/redis,soveran/redis,cloudrain21/redis,hgl888/redis,mumingv/redis-3.0-annotated,july2993/redis,harrisonfeng/redis,mpalmer/redis,shreesundara/redis,xujunhai1991/redis,GrimDerp/redis,jermnelson/redis,abhiklodh/redis,rogerlz/redis,YongMan/redis,Wangyao14cyy/redis,ipmobiletech/redis,huangz1990/annotated_redis_source,gilala/redis,mingyaaaa/redis,nuxeh/redis,yybirdcf/learn-redis,zhiliaoniu/redis,neomantra/redis,hornen/redis,mengzhejin/RedisStudy,YongMan/redis,yuhc/redis-benchmark-enhanced,mengyou0304/redis,atreeyang/redis,j0hnma/hszredis,pietern/redis,mengyou0304/redis,abhiklodh/redis,Sciumo/redis,mverrilli/redis,mcanthony/redis,jacklee0810/redis-3.0-annotated,jacklee0810/annotated_redis_source,gongice/redis-3.0-annotated,StevenTsai/redis,xuguruogu/redis,alenslan/redis,seandsky/redis,YuraLukashik/redis,weizijun/redis,z-fork/redis,simplestbest/redis,PKRoma/redis,fengshao0907/redis-3.0-annotated,nuxeh/redis,roth1002/redis,huangz1990/redis-3.0-annotated,GrimDerp/redis,Aliceljm1/redis-3.0-annotated,Hailei/redis,devaos/redis,magastzheng/redis-3.0-annotated,MSOpenTech/redis,mpalmer/redis,gilala/bjredis,gaoxianglong/redis,mgk/redis,gilala/hredis,zguangyu/redis,pkdevbox/redis,janekmi/redis,ttuna/msot-redis,wuyu201321060203/redis-3.0-annotated,sunlianqiang/redis-3.0-annotated,Soledad89/redis,ChanningDuan/annotated_redis_source,spinlock/redis,alenslan/redis,kmiku7/redis,pmem/redis,badboy/redis,wuxiaowei907/annotated_redis_source,taoguan/redis,Aliceljm1/redis,ouyangkongtong/redis,mcanthony/redis,dramenk/annotated_redis_source,msn217/redis-3.0-annotated,qiyang0221/redis,darksideofthemoo/redis-histogram,timothyohare/3rdPartySrc-redis,roth1002/redis,tellapart/redis,fengshao0907/annotated_redis_source,Markgorden/redis,cusspvz/redis,yuzhangjob/redis-3.0-annotated-unstable,wbailey5/redis,tidatida/annotated_redis_source,programmecat/redis,xlzhan/redis,badboy/redis,allengaller/redis,ncopa/redis,darksideofthemoo/redis-histogram,jxwr/redis,onlymellb/redis-3.0-annotated,j0hnma/hszredis,zhoudayang/redis,mverrilli/redis,Aaron1992/redis,NBSW/redis,190235047/redis,j0hnma/szredis,jackyan/redis,ErikDubbelboer/redis,yuhc/redis-benchmark-enhanced,taoguan/redis,pietern/redis,davidradunz/redis,gilala/hbjredis,SyntaxStacks/redis,simplestbest/redis,mumingv/redis-3.0-annotated,unasm/redis-3.0-annotated,wuyu201321060203/redis-3.0-annotated,gechong/redis-3.0-annotated,drinkthere/redis-3.0-annotated,StevenTsai/redis,mumingv/redis,tellapart/redis,z-fork/redis,roth1002/redis,splitice/redis,xlzhan/redis,z-fork/redis,arijitvt/redis,huyuezheng/redis,aim-for-better/redis,MasahikoSawada/redis,universsky/redis,xuzhezhaozhao/redis_reading,supasate/redis,YuraLukashik/redis,AALEKH/redis,rrsean/redis-3.0-annotated,yuzhangjob/redis-3.0-annotated-unstable,himoca/redis,yossigo/redis,Aliceljm1/redis,jbochi/redis,gspandy/annotated_redis_source,Markgorden/redis,charsyam/redis,duanx/redis,ituncle/redis,sunheehnus/redis,brg-liuwei/redis,nilyang/redis-tdd-annotation,kaushik94/redis,tzq668766/redis-3.0-annotated,dayuoba/redis,190235047/redis,ipmobiletech/redis,dayuoba/redis,aim-for-better/redis,shining-yang/redis,ketor/redis,harrisonfeng/redis,gilala/hredis,tanghaodong25/redis,narma/redis,gaoxianglong/redis,NBSW/redis,dramenk/annotated_redis_source,soloestoy/redis,dongqifan2/redis-3.0-annotated,francischan714/redis,twskipper/redis,StevenTsai/redis,shshlzh/redis-3.0-annotated,sunlianqiang/redis-3.0-annotated,ouyangkongtong/redis,weizijun/redis,devaos/redis,zhcy/redis,valdsJohn/redis,GitHubMota/redis,oranagra/redis,elkingtonmcb/redis,ton31337/redis,ofirluzon/redis,itamarhaber/redis,neomantra/redis,mrb/redis,charsyam/redis,ramonsnir/redis,hgl888/redis,StevenTsai/redis,louisliangjun/redis,ErikDubbelboer/redis,kaushik94/redis,hedisdb/hedis,ChaosCoo/annotated_redis_source,fengshao0907/redis-3.0-annotated,holstvoogd/redis,gspandy/annotated_redis_source,GrimDerp/redis,aluzzardi/redis,Cisphyx/redis-websockets,hedisdb/hedis,itamarhaber/redis,jackyan/redis,miaoyc1989/redis-3.0-annotated,ituncle/redis,colstrom/redis,allengaller/redis,jackyan/redis,miaoyc1989/redis-3.0-annotated,MasahikoSawada/redis,ReadCode/redis-3.0-annotated,rogerlz/redis,aluzzardi/redis,wujf/redis,soveran/redis,4396/redis,timothyohare/3rdPartySrc-redis,antirez/redis,190235047/redis,GitHubMota/redis,taoguan/redis,mrb/redis,twskipper/redis,riyan8250/redis,flashbuckets/redis,gilala/redis,qiyang0221/redis,cusspvz/redis,mumingv/redis,tellapart/redis,miaoyc1989/redis-3.0-annotated,rouzier/redis,arijitvt/redis,jingjidejuren/redis,josiahcarlson/redis,fankeke/redis-3.0-annotated,seppo0010/redis,itugs/redis,0x55/redis-3.0-annotated,vincent-vivian-liu/redis,whille/redis-3.0-annotated,hgl888/redis,jxwr/redis,izhoujie/redis,whille/redis-3.0-annotated,holstvoogd/redis,valdsJohn/redis,mumingv/redis-3.0-annotated,takeshineshiro/redis,pedigree/redis,pkdevbox/redis,brg-liuwei/redis,hawkchch/redis,LongXQ/redis,HeartSaVioR/redis,rogerchina/redis,aim-for-better/redis,buobao/redis-3.0-annotated,wangyikai/redis,ouyangkongtong/redis,shreesundara/redis,wuyu201321060203/redis-3.0-annotated,nnog/redis,fengshao0907/redis,weizijun/redis,fengshao0907/annotated_redis_source,JoeWoo/redis,gilala/hbjredis,pedigree/redis,tanghaodong25/redis,supasate/redis,mengzhejin/RedisStudy,antirez/redis,jacklee0810/redis-3.0-annotated,charsyam/redis,yybirdcf/learn-redis,splitice/redis,twskipper/redis,cnbin/redis,wenxueliu/redis_comment,PKRoma/redis,blackmady/redis,machicao2013/redis-source-annotated,allengaller/redis,jbochi/parallel_redis,spinlock/redis,Aaron1992/redis,shshlzh/redis-3.0-annotated,rogerchina/redis,HunanTV/redis,ituncle/redis,allengaller/redis,huangz1990/redis-3.0-annotated,JoeWoo/redis,Aaron1992/redis,zhiliaoniu/redis,splitice/redis,GitHubMota/redis,colstrom/redis,jasonkying/redis,Markgorden/redis,Aliceljm1/redis,fengshao0907/redis,hornen/redis,ketor/redis,MasahikoSawada/redis,viongpanzi/annotated_redis_source,ctripcorp/redis,190235047/redis,harrisonfeng/redis,nilyang/redis-tdd-annotation,seppo0010/rlite-server,ttuna/msot-redis,oranagra/redis,AALEKH/redis,modulexcite/redis,maodeyi/redis_lua,RepmujNetsik/redis,dayuoba/redis,universsky/redis,hhli/redis,netroby/redis,Hailei/redis,RepmujNetsik/redis,tjschuck/redis,mattsta/redis,Sciumo/redis,arijitvt/redis,mengzhejin/RedisStudy,buobao/redis-3.0-annotated,mingyaaaa/redis,OmarQunsul/graph-redis,ituncle/redis,davidradunz/redis,seandsky/redis,0x20h/redis,shining-yang/redis,ramonsnir/redis,devaos/redis,moonbingbing/redis-3.0-annotated,adamweixuan/redis-3.0-annotated,duanx/redis,supasate/redis,zhiliaoniu/redis,izhoujie/redis,YuanZhewei/redis,riyan8250/redis,modulexcite/redis,gilala/redis,tjschuck/redis,PradheepShrinivasan/redis,adamweixuan/redis-3.0-annotated,Aliceljm1/redis-3.0-annotated,rouzier/redis,abhiklodh/redis,darksideofthemoo/redis-histogram,blackmady/redis,4396/redis,wprice/redis,devaos/redis,programmecat/redis,itugs/redis,wuyu201321060203/redis-3.0-annotated,hhli/redis,nilyang/redis-tdd-annotation,LongXQ/redis,janekmi/redis,saisai/redis,adamweixuan/redis-3.0-annotated,Wangyao14cyy/redis,cnbin/redis,HouKangkang/redis-3.0-annotated,citusdata/redis,Markgorden/redis,ofirluzon/redis,josephholsten/redis,francischan714/redis,xlzhan/redis,honestme/redis,alenslan/redis,clamoriniere1A/redis,yuhc/redis-benchmark-enhanced,4396/redis,gilala/hbjredis,OmarQunsul/graph-redis,zhaobo1023/redis-3.0-annotated,tidatida/annotated_redis_source,citusdata/redis,himoca/redis,blackmady/redis,a-pavlov/redis,zhcy/redis,gaoxianglong/redis,wprice/redis,gspandy/annotated_redis_source,ChaosCoo/annotated_redis_source,roth1002/redis,ofirluzon/redis,slfs007/mk-redis,LongXQ/redis,takeshineshiro/redis,huyuezheng/redis,mengyou0304/redis,neomantra/redis,PKRoma/redis,netroby/redis,ncopa/redis,yossigo/redis,YuanZhewei/redis,pcarrier/redis,shining-yang/redis,danny200309/annotated_redis_source,haima-zju/redis-3.0-annotated,csuhawk/redis,soloestoy/redis,Sciumo/redis,saisai/redis,modulexcite/redis,Wangyao14cyy/redis,programmecat/redis,ncopa/redis,xuguruogu/redis,valdsJohn/redis,guker/redis,pmem/redis,blackmady/redis,itugs/redis,huangz1990/redis-3.0-annotated,janekmi/redis,machicao2013/redis-source-annotated,h0x91b/redis,wenxueliu/redis_comment,AALEKH/redis,narma/redis,healerkx/redis