inmem.StackSender.Add returns a reference to the previous chain
inmem.StackSender.Add returns a reference to the previous chain

Signed-off-by: Solomon Hykes <510d74b69d9d43b60b6f6aa9d95e9f9c9497f815@docker.com>

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a/SwarmACLs,abronan/swarm,rutulpatel/swarm,ehazlett/swarm,cgvarela/swarm,LukasBacigal/swarm,riuvshin/swarm,CodeNow/swarm,docker-zh/docker.github.io,menglingwei/denverdino.github.io,joaofnfernandes/docker.github.io,LukasBacigal/swarm,shin-/docker.github.io,auzias/swarm,JimGalasyn/docker.github.io,denverdino/swarm,anweiss/docker.github.io,resouer/swarm,ch3lo/swarm,echupriyanov/swarm,pssahi/swarm,therealbill/swarm,dims/swarm,JimGalasyn/docker.github.io,vieux/swarm,tnachen/swarm,moxiegirl/swarm,Aorjoa/swarm,BSWANG/swarm,gdevillele/docker.github.io,shubheksha/docker.github.io,cgvarela/swarm,FollowMyDev/swarm,alexisbellido/docker.github.io,bdwill/docker.github.io,allencloud/swarm,allencloud/swarm,JimGalasyn/docker.github.io,moxiegirl/swarm,shubheksha/docker.github.io,gonkulator/swarm,jdamick/swarm,rillig/docker.github.io,BSWANG/denverdino.github.io,docker/docker.github.io,shot/swarm,mountkin/swarm,bsmr-docker/swarm,FreedomWangLi/swarm,LuisBosquez/docker.github.io,thaJeztah/docker.github.io,danix800/docker.github.io,gdevillele/docker.github.io,qianzhangxa/swarm,NunoEdgarGub1/swarm,denverdino/denverdino.github.io,everett-toews/swarm,echupriyanov/swarm,chanwit/swarm,swarm-hooks/swarm,aduermael/docker.github.io,ealang/swarm,shin-/docker.github.io,affo/swarm,denverdino/docker.github.io,ejholmes/swarm,menglingwei/denverdino.github.io,docker-zh/docker.github.io,linecheng/swarm,joeuo/docker.github.io,jay-lau/swarm,morpheyesh/swarm,denverdino/docker.github.io,raoofm/swarm,BSWANG/denverdino.github.io,dnephin/swarm,akerbis/armhf-swarm,londoncalling/docker.github.io,beni55/swarm-1,danix800/docker.github.io,kunalkushwaha/swarm,yp-engineering/swarm,denverdino/docker.github.io