Revert "Fix race conditions in takeUntilReplacement()"
Revert "Fix race conditions in takeUntilReplacement()"

This reverts commit 10cf9217a1f05d1d5c6c44f557579e2617ffbf57.

GuitarPlayer-Ma/ReactiveCocoa,zhiwen1024/ReactiveCocoa,pzw224/ReactiveCocoa,dskatz22/ReactiveCocoa,LHDsimon/ReactiveCocoa,tonyarnold/ReactiveCocoa,chao95957/ReactiveCocoa,stevielu/ReactiveCocoa,qq644531343/ReactiveCocoa,on99/ReactiveCocoa,kaylio/ReactiveCocoa,xulibao/ReactiveCocoa,zhukaixy/ReactiveCocoa,Juraldinio/ReactiveCocoa,esttorhe/ReactiveCocoa,smilypeda/ReactiveCocoa,sugar2010/ReactiveCocoa,valleyman86/ReactiveCocoa,kevin-zqw/ReactiveCocoa,Pingco/ReactiveCocoa,rpowelll/ReactiveCocoa,tonyli508/ReactiveCocoa,SanChain/ReactiveCocoa,zhaoguohui/ReactiveCocoa,JackLian/ReactiveCocoa,richeterre/ReactiveCocoa,andersio/ReactiveCocoa,Farteen/ReactiveCocoa,dullgrass/ReactiveCocoa,cogddo/ReactiveCocoa,tzongw/ReactiveCocoa,sdhzwm/ReactiveCocoa,imkerberos/ReactiveCocoa,tzongw/ReactiveCocoa,jeelun/ReactiveCocoa,KuPai32G/ReactiveCocoa,dullgrass/ReactiveCocoa,hj3938/ReactiveCocoa,bscarano/ReactiveCocoa,Ethan89/ReactiveCocoa,mtxs007/ReactiveCocoa,add715/ReactiveCocoa,nikita-leonov/ReactiveCocoa,SuPair/ReactiveCocoa,dskatz22/ReactiveCocoa,dz1111/ReactiveCocoa,esttorhe/ReactiveCocoa,juliangrosshauser/ReactiveCocoa,Ray0218/ReactiveCocoa,natan/ReactiveCocoa,CQXfly/ReactiveCocoa,monkeydbobo/ReactiveCocoa,AndyZhaoHe/ReactiveCocoa,DreamHill/ReactiveCocoa,PSPDFKit-labs/ReactiveCocoa,yaoxiaoyong/ReactiveCocoa,ReactiveCocoa/ReactiveSwift,mtxs007/ReactiveCocoa,ioshger0125/ReactiveCocoa,ericzhou2008/ReactiveCocoa,ShawnLeee/ReactiveCocoa,stevielu/ReactiveCocoa,liufeigit/ReactiveCocoa,esttorhe/ReactiveCocoa,longv2go/ReactiveCocoa,dskatz22/ReactiveCocoa,xumaolin/ReactiveCocoa,juliangrosshauser/ReactiveCocoa,icepy/ReactiveCocoa,xulibao/ReactiveCocoa,GuitarPlayer-Ma/ReactiveCocoa,esttorhe/ReactiveCocoa,yizzuide/ReactiveCocoa,terry408911/ReactiveCocoa,JackLian/ReactiveCocoa,leelili/ReactiveCocoa,rpowelll/ReactiveCocoa,jsslai/ReactiveCocoa,LHDsimon/ReactiveCocoa,clg0118/ReactiveCocoa,chieryw/ReactiveCocoa,kaylio/ReactiveCocoa,andersio/ReactiveCocoa,JackLian/ReactiveCocoa,icepy/ReactiveCocoa,kevin-zqw/ReactiveCocoa,msdgwzhy6/ReactiveCocoa,Ethan89/ReactiveCocoa,wpstarnice/ReactiveCocoa,cstars135/ReactiveCocoa,terry408911/ReactiveCocoa,CCOOOOLL/ReactiveCocoa,DongDongDongDong/ReactiveCocoa,nickcheng/ReactiveCocoa,jrmiddle/ReactiveCocoa,xiaoliyang/ReactiveCocoa,hoanganh6491/ReactiveCocoa,fhchina/ReactiveCocoa,paulyoung/ReactiveCocoa,JohnJin007/ReactiveCocoa,loupman/ReactiveCocoa,hj3938/ReactiveCocoa,add715/ReactiveCocoa,zhenlove/ReactiveCocoa,DreamHill/ReactiveCocoa,almassapargali/ReactiveCocoa,libiao88/ReactiveCocoa,xiaobing2007/ReactiveCocoa,j364960953/ReactiveCocoa,hilllinux/ReactiveCocoa,on99/ReactiveCocoa,DreamHill/ReactiveCocoa,jeelun/ReactiveCocoa,huiping192/ReactiveCocoa,Ricowere/ReactiveCocoa,cnbin/ReactiveCocoa,kiurentu/ReactiveCocoa,itschaitanya/ReactiveCocoa,jsslai/ReactiveCocoa,Eveian/ReactiveCocoa,CCOOOOLL/ReactiveCocoa,howandhao/ReactiveCocoa,KuPai32G/ReactiveCocoa,AndyZhaoHe/ReactiveCocoa,on99/ReactiveCocoa,ceekayel/ReactiveCocoa,sandyway/ReactiveCocoa,ikesyo/ReactiveCocoa,OnTheWay1988/ReactiveCocoa,Farteen/ReactiveCocoa,towik/ReactiveCocoa,j364960953/ReactiveCocoa,liufeigit/ReactiveCocoa,yangshengchaoios/ReactiveCocoa,eyu1988/ReactiveCocoa,jaylib/ReactiveCocoa,shuxiashusheng/ReactiveCocoa,sdhzwm/ReactiveCocoa,llb1119/test,Farteen/ReactiveCocoa,zxq3220122/ReactiveCocoa,zzzworm/ReactiveCocoa,bscarano/ReactiveCocoa,zhenlove/ReactiveCocoa,PSPDFKit-labs/ReactiveCocoa,kevin-zqw/ReactiveCocoa,pzw224/ReactiveCocoa,huiping192/ReactiveCocoa,RuiAAPeres/ReactiveCocoa,natan/ReactiveCocoa,brasbug/ReactiveCocoa,ikesyo/ReactiveCocoa,FelixYin66/ReactiveCocoa,walkingsmarts/ReactiveCocoa,luerhouhou/ReactiveCocoa,rpowelll/ReactiveCocoa,zhaoguohui/ReactiveCocoa,wpstarnice/ReactiveCocoa,tornade0913/ReactiveCocoa,Ray0218/ReactiveCocoa,eyu1988/ReactiveCocoa,yangshengchaoios/ReactiveCocoa,nickcheng/ReactiveCocoa,zhiwen1024/ReactiveCocoa,wangqi211/ReactiveCocoa,valleyman86/ReactiveCocoa,WEIBP/ReactiveCocoa,shuxiashusheng/ReactiveCocoa,Khan/ReactiveCocoa,hoanganh6491/ReactiveCocoa,longv2go/ReactiveCocoa,yytong/ReactiveCocoa,mattpetters/ReactiveCocoa,tonyli508/ReactiveCocoa,ReactiveCocoa/ReactiveSwift,xulibao/ReactiveCocoa,fhchina/ReactiveCocoa,vincentiss/ReactiveCocoa,CQXfly/ReactiveCocoa,yaoxiaoyong/ReactiveCocoa,hbucius/ReactiveCocoa,dachaoisme/ReactiveCocoa,chao95957/ReactiveCocoa,buildo/ReactiveCocoa,ioshger0125/ReactiveCocoa,llb1119/test,dullgrass/ReactiveCocoa,yizzuide/ReactiveCocoa,monkeydbobo/ReactiveCocoa,SanChain/ReactiveCocoa,richeterre/ReactiveCocoa,almassapargali/ReactiveCocoa,gengjf/ReactiveCocoa,jrmiddle/ReactiveCocoa,alvinvarghese/ReactiveCocoa,alvinvarghese/ReactiveCocoa,Khan/ReactiveCocoa,ohwutup/ReactiveCocoa,yaoxiaoyong/ReactiveCocoa,hbucius/ReactiveCocoa,monkeydbobo/ReactiveCocoa,zzzworm/ReactiveCocoa,dachaoisme/ReactiveCocoa,Liquidsoul/ReactiveCocoa,Juraldinio/ReactiveCocoa,zxq3220122/ReactiveCocoa,leichunfeng/ReactiveCocoa,WEIBP/ReactiveCocoa,stupidfive/ReactiveCocoa,BrooksWon/ReactiveCocoa,msdgwzhy6/ReactiveCocoa,towik/ReactiveCocoa,tiger8888/ReactiveCocoa,PSPDFKit-labs/ReactiveCocoa,takeshineshiro/ReactiveCocoa,ohwutup/ReactiveCocoa,zhukaixy/ReactiveCocoa,200895045/ReactiveCocoa,chieryw/ReactiveCocoa,ddc391565320/ReactiveCocoa,zhigang1992/ReactiveCocoa,taylormoonxu/ReactiveCocoa,zhigang1992/ReactiveCocoa,RuiAAPeres/ReactiveCocoa,beni55/ReactiveCocoa,calebd/ReactiveCocoa,kaylio/ReactiveCocoa,longv2go/ReactiveCocoa,isghe/ReactiveCocoa,wpstarnice/ReactiveCocoa,xumaolin/ReactiveCocoa,nickcheng/ReactiveCocoa,BlessNeo/ReactiveCocoa,xiaoliyang/ReactiveCocoa,AndyZhaoHe/ReactiveCocoa,Eveian/ReactiveCocoa,luerhouhou/ReactiveCocoa,xiaobing2007/ReactiveCocoa,Ethan89/ReactiveCocoa,libiao88/ReactiveCocoa,hj3938/ReactiveCocoa,itschaitanya/ReactiveCocoa,shaohung001/ReactiveCocoa,shaohung001/ReactiveCocoa,Pingco/ReactiveCocoa,takeshineshiro/ReactiveCocoa,gengjf/ReactiveCocoa,LHDsimon/ReactiveCocoa,itschaitanya/ReactiveCocoa,jsslai/ReactiveCocoa,jeelun/ReactiveCocoa,BlessNeo/ReactiveCocoa,goodheart/ReactiveCocoa,fanghao085/ReactiveCocoa,cstars135/ReactiveCocoa,AlanJN/ReactiveCocoa,windgo/ReactiveCocoa,stupidfive/ReactiveCocoa,sdhzwm/ReactiveCocoa,yangyangluoluo/ReactiveCocoa,leichunfeng/ReactiveCocoa,ohwutup/ReactiveCocoa,yonekawa/ReactiveCocoa,jackywpy/ReactiveCocoa,taylormoonxu/ReactiveCocoa,tornade0913/ReactiveCocoa,shaohung001/ReactiveCocoa,ioshger0125/ReactiveCocoa,sujeking/ReactiveCocoa,windgo/ReactiveCocoa,zhenlove/ReactiveCocoa,zhiwen1024/ReactiveCocoa,fhchina/ReactiveCocoa,zzzworm/ReactiveCocoa,almassapargali/ReactiveCocoa,FelixYin66/ReactiveCocoa,huiping192/ReactiveCocoa,JohnJin007/ReactiveCocoa,mattpetters/ReactiveCocoa,terry408911/ReactiveCocoa,zzqiltw/ReactiveCocoa,yizzuide/ReactiveCocoa,CCOOOOLL/ReactiveCocoa,isghe/ReactiveCocoa,CQXfly/ReactiveCocoa,lixar/ReactiveCocoa,DongDongDongDong/ReactiveCocoa,jackywpy/ReactiveCocoa,mxxiv/ReactiveCocoa,yytong/ReactiveCocoa,AlanJN/ReactiveCocoa,goodheart/ReactiveCocoa,andersio/ReactiveCocoa,sugar2010/ReactiveCocoa,jaylib/ReactiveCocoa,smilypeda/ReactiveCocoa,BrooksWon/ReactiveCocoa,yangyangluoluo/ReactiveCocoa,walkingsmarts/ReactiveCocoa,bensonday/ReactiveCocoa,bensonday/ReactiveCocoa,OnTheWay1988/ReactiveCocoa,mattpetters/ReactiveCocoa,wangqi211/ReactiveCocoa,xiaoliyang/ReactiveCocoa,vincentiss/ReactiveCocoa,hbucius/ReactiveCocoa,ztchena/ReactiveCocoa,ShawnLeee/ReactiveCocoa,natestedman/ReactiveCocoa,Rupert-RR/ReactiveCocoa,richeterre/ReactiveCocoa,icepy/ReactiveCocoa,stupidfive/ReactiveCocoa,juliangrosshauser/ReactiveCocoa,jrmiddle/ReactiveCocoa,chao95957/ReactiveCocoa,loupman/ReactiveCocoa,smilypeda/ReactiveCocoa,jam891/ReactiveCocoa,KJin99/ReactiveCocoa,yonekawa/ReactiveCocoa,fanghao085/ReactiveCocoa,hoanganh6491/ReactiveCocoa,dz1111/ReactiveCocoa,mtxs007/ReactiveCocoa,SuPair/ReactiveCocoa,beni55/ReactiveCocoa,fanghao085/ReactiveCocoa,gengjf/ReactiveCocoa,OnTheWay1988/ReactiveCocoa,leichunfeng/ReactiveCocoa,luerhouhou/ReactiveCocoa,yangyangluoluo/ReactiveCocoa,SanChain/ReactiveCocoa,jaylib/ReactiveCocoa,Eveian/ReactiveCocoa,Liquidsoul/ReactiveCocoa,victorlin/ReactiveCocoa,clg0118/ReactiveCocoa,Rupert-RR/ReactiveCocoa,add715/ReactiveCocoa,ceekayel/ReactiveCocoa,takeshineshiro/ReactiveCocoa,emodeqidao/ReactiveCocoa,cogddo/ReactiveCocoa,towik/ReactiveCocoa,200895045/ReactiveCocoa,victorlin/ReactiveCocoa,natan/ReactiveCocoa,xiaobing2007/ReactiveCocoa,leelili/ReactiveCocoa,dachaoisme/ReactiveCocoa,j364960953/ReactiveCocoa,ReactiveCocoa/ReactiveSwift,yoichitgy/ReactiveCocoa,walkingsmarts/ReactiveCocoa,lixar/ReactiveCocoa,zhukaixy/ReactiveCocoa,windgo/ReactiveCocoa,alvinvarghese/ReactiveCocoa,yytong/ReactiveCocoa,KuPai32G/ReactiveCocoa,chieryw/ReactiveCocoa,Juraldinio/ReactiveCocoa,imkerberos/ReactiveCocoa,libiao88/ReactiveCocoa,tzongw/ReactiveCocoa,tiger8888/ReactiveCocoa,msdgwzhy6/ReactiveCocoa,zxq3220122/ReactiveCocoa,beni55/ReactiveCocoa,brasbug/ReactiveCocoa,hilllinux/ReactiveCocoa,natestedman/ReactiveCocoa,yangshengchaoios/ReactiveCocoa,ddc391565320/ReactiveCocoa,howandhao/ReactiveCocoa,GuitarPlayer-Ma/ReactiveCocoa,eyu1988/ReactiveCocoa,RuiAAPeres/ReactiveCocoa,jam891/ReactiveCocoa,buildo/ReactiveCocoa,valleyman86/ReactiveCocoa,WEIBP/ReactiveCocoa,nickcheng/ReactiveCocoa,goodheart/ReactiveCocoa,DongDongDongDong/ReactiveCocoa,tonyarnold/ReactiveCocoa,Pingco/ReactiveCocoa,Ricowere/ReactiveCocoa,nikita-leonov/ReactiveCocoa,zzqiltw/ReactiveCocoa,paulyoung/ReactiveCocoa,loupman/ReactiveCocoa,BlessNeo/ReactiveCocoa,natestedman/ReactiveCocoa,yonekawa/ReactiveCocoa,vincentiss/ReactiveCocoa,sandyway/ReactiveCocoa,cogddo/ReactiveCocoa,wangqi211/ReactiveCocoa,zzqiltw/ReactiveCocoa,hilllinux/ReactiveCocoa,tiger8888/ReactiveCocoa,AlanJN/ReactiveCocoa,howandhao/ReactiveCocoa,yoichitgy/ReactiveCocoa,OneSmallTree/ReactiveCocoa,cnbin/ReactiveCocoa,tornade0913/ReactiveCocoa,xumaolin/ReactiveCocoa,zhigang1992/ReactiveCocoa,brasbug/ReactiveCocoa,FelixYin66/ReactiveCocoa,bscarano/ReactiveCocoa,ceekayel/ReactiveCocoa,jaylib/ReactiveCocoa,leelili/ReactiveCocoa,SuPair/ReactiveCocoa,OneSmallTree/ReactiveCocoa,yoichitgy/ReactiveCocoa,huiping192/ReactiveCocoa,shuxiashusheng/ReactiveCocoa,tonyarnold/ReactiveCocoa,llb1119/test,cstars135/ReactiveCocoa,Liquidsoul/ReactiveCocoa,Ray0218/ReactiveCocoa,lixar/ReactiveCocoa,sandyway/ReactiveCocoa,Rupert-RR/ReactiveCocoa,200895045/ReactiveCocoa,Ricowere/ReactiveCocoa,ddc391565320/ReactiveCocoa,sujeking/ReactiveCocoa,bensonday/ReactiveCocoa,imkerberos/ReactiveCocoa,jackywpy/ReactiveCocoa,pzw224/ReactiveCocoa,liufeigit/ReactiveCocoa,mxxiv/ReactiveCocoa,buildo/ReactiveCocoa,paulyoung/ReactiveCocoa,ztchena/ReactiveCocoa,KJin99/ReactiveCocoa,calebd/ReactiveCocoa,zhaoguohui/ReactiveCocoa,mxxiv/ReactiveCocoa,cnbin/ReactiveCocoa,KJin99/ReactiveCocoa,ericzhou2008/ReactiveCocoa,stevielu/ReactiveCocoa,Khan/ReactiveCocoa,sujeking/ReactiveCocoa,nikita-leonov/ReactiveCocoa,tonyli508/ReactiveCocoa,ericzhou2008/ReactiveCocoa,kiurentu/ReactiveCocoa,emodeqidao/ReactiveCocoa,JohnJin007/ReactiveCocoa,isghe/ReactiveCocoa,emodeqidao/ReactiveCocoa,dz1111/ReactiveCocoa,victorlin/ReactiveCocoa,calebd/ReactiveCocoa,ShawnLeee/ReactiveCocoa,kiurentu/ReactiveCocoa,clg0118/ReactiveCocoa,qq644531343/ReactiveCocoa,OneSmallTree/ReactiveCocoa,qq644531343/ReactiveCocoa,ztchena/ReactiveCocoa,taylormoonxu/ReactiveCocoa,sugar2010/ReactiveCocoa,jam891/ReactiveCocoa,Ricowere/ReactiveCocoa,BrooksWon/ReactiveCocoa