don't recalc ip csum from scratch on ttl decrement
don't recalc ip csum from scratch on ttl decrement

EverythingMe/flannel,adiclepcea/flannel,ingvagabund/flannel,endocode/flannel,bprashanth/flannel,svdata/flannel,wikimedia/operations-debs-flannel,wikimedia/operations-debs-flannel,kelcecil/flannel,bprashanth/flannel,coreos/flannel,flynn/flannel,coreos/flannel,lihuanghai/flannel,eyakubovich/flannel,eparis/flannel,MohdAhmad/flannel,Yhgenomics/flannel,imzhulei/flannel,Yhgenomics/flannel,svdata/flannel,eyakubovich/flannel,benbjohnson/flannel,dcbw/flannel,benbjohnson/flannel,rranshous/flannel,lihuanghai/flannel,endocode/flannel,sujitfulse/flannel,kelcecil/flannel,kelcecil/flannel,ingvagabund/flannel,MohdAhmad/flannel,wikimedia/operations-debs-flannel,cusspvz/flannel,adiclepcea/flannel,lvlv/flannel,jonboulle/flannel,adiclepcea/flannel,eyakubovich/flannel,cusspvz/flannel,flynn/flannel,svdata/flannel,cusspvz/flannel,imzhulei/flannel,lihuanghai/flannel,jonboulle/flannel,flynn/flannel,rranshous/flannel,imzhulei/flannel,EverythingMe/flannel,eparis/flannel,eparis/flannel,sujitfulse/flannel,endocode/flannel,ingvagabund/flannel,jonboulle/flannel,lvlv/flannel,EverythingMe/flannel,coreos/flannel,rranshous/flannel,dcbw/flannel,bprashanth/flannel,sujitfulse/flannel,MohdAhmad/flannel,benbjohnson/flannel,dcbw/flannel,lvlv/flannel,Yhgenomics/flannel