snapshot: consider unrelated snapshots at a similar level first This new step is inserted before considering using a level-N snapshot as a base for a level-N+1 snapshot. We first check if existing level-N+1 snapshots using the same base would be a suitable base for a level-N+2 snapshot. This increases snapshot reuse and limits the risk of snapshot explosion in very branchy repositories. Using a "deeper" snapshot as the base also results in a smaller snapshot since it builds a level-N+2 intermediate snapshot instead of an N+1 one. This logic is similar for the one we added in a previous commit. In that previous commit is only applied to level-0 "siblings". We can see this effect in the test repository. Snapshots moved from lower levels to higher levels.