Add a nil check for sandbox.osSbox
Add a nil check for sandbox.osSbox

Signed-off-by: Santhosh Manohar <0806b0927a65802677e1bc58a740a42f957953d7@docker.com>

trebonian/docker,konstruktoid/docker-upstream,djs55/docker,Mokolea/docker,moby/moby,yosifkit/docker,nawawi/docker,nawawi/docker,Mokolea/docker,jthelin/docker,Mokolea/docker,jameszhan/docker,yosifkit/docker,jimjag/docker,cpuguy83/docker,trebonian/docker,thaJeztah/docker,mahak/docker,jimjag/docker,nawawi/docker,AkihiroSuda/docker,gnailuy/docker,jameszhan/docker,vdemeester/docker,yosifkit/docker,trebonian/docker,vdemeester/docker,jimjag/docker,thaJeztah/docker,moul/docker,jthelin/docker,flavio/docker,AkihiroSuda/docker,moby/moby,docker/docker,flavio/docker,Ramzec/docker,nalind/docker,paralin/docker,nalind/docker,gnailuy/docker,moul/docker,Ramzec/docker,moby/moby,bearstech/moby,konstruktoid/docker-upstream,flavio/docker,AkihiroSuda/docker,bearstech/moby,bearstech/moby,cpuguy83/docker,nalind/docker,Mokolea/docker,bearstech/moby,konstruktoid/docker-upstream,Ramzec/docker,mahak/docker,djs55/docker,konstruktoid/docker-upstream,Ramzec/docker,docker/docker,gnailuy/docker,flavio/docker,AkihiroSuda/docker,yosifkit/docker,nalind/docker,paralin/docker,nawawi/docker,jimjag/docker,thaJeztah/docker,docker/docker,moul/docker,cpuguy83/docker,thaJeztah/docker,paralin/docker,moby/moby,cpuguy83/docker,jameszhan/docker,djs55/docker,gnailuy/docker,moul/docker,mahak/docker,vdemeester/docker,paralin/docker,mahak/docker,trebonian/docker