Unmerge Catalog Part

Put a merged-away identity back, with the lots that moved with it.

Reverses exactly what the merge did and nothing else. The lots come back with their quantities, costs, receiving and QC logs and placements untouched -- the same rule in both directions, since folding names never moved metal and unfolding them cannot either.

Only the aliases the merge ADDED are stripped, and a cover is given back only if the winner borrowed it. Both facts were written down at merge time (master_catalog_parts.merge_effects); after the fold there is no way to tell a borrowed cover from a chosen one, or an alias the merge introduced from one the winner always had.