Development record

readme.created can still vouch for an owner's README.md when no abcd run sees the created file gone: abcd creates README.md, the owner answers --readme-parts none (the file is left blank, the record stands), deletes the file and writes a placeholder holding only blank lines before any install or uninstall runs; uninstall then deletes the placeholder as the file abcd created. An install or uninstall that finds README.md gone now clears the record (lane-3 fix round 1, run-2610110908176735), which closes every sequence with an abcd run in between, but a boolean cannot tell the file abcd wrote from one written in its place. The loss is whitespace only.