Don't treat non-nil output as error in ChainExists
Don't treat non-nil output as error in ChainExists

ChainExists should not treat non-nil output as
error because there is always going to be some
output while dumping iptable rules.

Signed-off-by: Jana Radhakrishnan <045898bda7d4800fe4909a9831e702ab79e266be@docker.com>

tgraf/libnetwork,mahak/libnetwork,hackersdotmu/libnetwork,abhi/libnetwork,msabansal/libnetwork,kolyshkin/libnetwork,mahak/libnetwork,mbanikazemi/libnetwork,docker/libnetwork,mYmNeo/libnetwork,docker/libnetwork,amitkris/libnetwork,cpuguy83/libnetwork,runcom/libnetwork,mbanikazemi/libnetwork,curtiszimmerman/libnetwork,vdemeester/libnetwork,anortef/libnetwork,amitkris/libnetwork,coolljt0725/libnetwork,WeiZhang555/libnetwork,sainath14/libnetwork,jimmycmh/libnetwork,msabansal/libnetwork,vdemeester/libnetwork,coolljt0725/libnetwork,kolyshkin/libnetwork,tgraf/libnetwork,fcrisciani/libnetwork,jmzwcn/libnetwork,mavenugo/libnetwork,vdemeester/libnetwork,allencloud/libnetwork,fcrisciani/libnetwork,mYmNeo/libnetwork,mavenugo/libnetwork,WeiZhang555/libnetwork,curtiszimmerman/libnetwork,cpuguy83/libnetwork,docker/libnetwork,tmakita/libnetwork,abhi/libnetwork,aboch/libnetwork_new,anortef/libnetwork,YujiOshima/libnetwork,aboch/libnetwork_new,tmakita/libnetwork,hackersdotmu/libnetwork,medallia/libnetwork,YujiOshima/libnetwork,kolyshkin/libnetwork,ityangchen/libnetwork,pyakpyak/libnetwork,jimmycmh/libnetwork,runcom/libnetwork,ityangchen/libnetwork,abhi/libnetwork,sainath14/libnetwork,mahak/libnetwork,pyakpyak/libnetwork,allencloud/libnetwork,medallia/libnetwork,medallia/libnetwork,jmzwcn/libnetwork