History of Mark::rings 2 changes

In crates/backdrop/src/mark.rs, lines 67–71 on 2f79b17e089af898bccb1236755e2c88c5868fac7edd5b4f5802c4544d1d3175. 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.