collapsing of zerolength branches after ladderization results in variable layout -> ladderize after collapse
collapsing of zerolength branches after ladderization results in variable layout
-> ladderize after collapse

fw1121/nextflu,blab/stability,fw1121/nextflu,blab/nextflu,doerlbh/Indie-nextflu,blab/nextflu,blab/stability,doerlbh/Indie-nextflu,blab/stability,fw1121/nextflu,blab/nextflu,blab/nextflu,blab/nextflu,blab/stability,doerlbh/Indie-nextflu,doerlbh/Indie-nextflu,fw1121/nextflu,blab/stability,blab/stability