evolve: rely on resolutionparent when relocating divergent csets As discussed with Pierre-Yves the current behavior of resolving content-divergence when parent changes: 1) First we decide the resolution parent (the parent where resolution cset will be based on) 2) Relocate both the divergent csets to the resolution parent (if a cset is already on resolution parent, nothing to do for it) 3) Perform 3-way merge to create the resolution cset of content-div This patch makes sure that we rely on that decided resolution parent, when relocating divergent csets to the parent where the resolution cset will be based on.