Make sure to not remove backends on stale notices
Make sure to not remove backends on stale notices

Sometimes you may get stale backend removal notices from gossip due to
some lingering state. If a stale backend notice is received and it is
already processed in this node ignore it rather than processing it.

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

fcrisciani/libnetwork,medallia/libnetwork,curtiszimmerman/libnetwork,allencloud/libnetwork,sainath14/libnetwork,vdemeester/libnetwork,abhi/libnetwork,medallia/libnetwork,mYmNeo/libnetwork,ityangchen/libnetwork,kolyshkin/libnetwork,sainath14/libnetwork,abhi/libnetwork,WeiZhang555/libnetwork,docker/libnetwork,docker/libnetwork,YujiOshima/libnetwork,WeiZhang555/libnetwork,cpuguy83/libnetwork,curtiszimmerman/libnetwork,tmakita/libnetwork,tmakita/libnetwork,mYmNeo/libnetwork,abhi/libnetwork,ityangchen/libnetwork,mahak/libnetwork,vdemeester/libnetwork,mahak/libnetwork,kolyshkin/libnetwork,mahak/libnetwork,msabansal/libnetwork,vdemeester/libnetwork,mbanikazemi/libnetwork,cpuguy83/libnetwork,mbanikazemi/libnetwork,kolyshkin/libnetwork,medallia/libnetwork,msabansal/libnetwork,allencloud/libnetwork,docker/libnetwork,YujiOshima/libnetwork,fcrisciani/libnetwork