History of Mark::rings 2 changes

In crates/backdrop/src/mark.rs, lines 67–71 on 529c703db24dc1ee425177acbd16d99050046e4ae6cd949493d6dc83515c0ee5. Every change that wrote or deleted one of these lines, or deleted a line from between them. Exact, because each line keeps its identity across edits; edits elsewhere in the file are not here. Also: oxy log -L 67,71:crates/backdrop/src/mark.rs.