History of Mark::rings 2 changes

In crates/backdrop/src/mark.rs, lines 67–71 on 851a26a2a6d1b5ed058be51bf362a81b285687aa6e3f78e5ce948e5b188a4e9c. 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.