History of Mark::rings 2 changes

In crates/backdrop/src/mark.rs, lines 67–71 on aa0bfbd11f02d9df4d579f4e8b0f0890d73629bc857878c414e882ebc42d3e85. 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.