Changes touching this path

• a fourth caller stops being able to read the merge's unsealed tree, because merge_trees now returns an Unsealed with no tree field and exactly two exits, one for the two callers that seal it into a change and one for the cherry-pick that re-seals under its own attributes (#1409) e14639ff · dbf3dbe6…

Renames are not followed. loot's tree maps a path to an address, so a rename is a delete and an add. This list is the history of the name, not of the bytes.