History of Mark::step 1 change

In crates/backdrop/src/mark.rs, lines 101–107 on 13b27cb2200c246f36d31d83144c047a61ccd07f12b9aa61c2a69c114bb11e2b. 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 101,107:crates/backdrop/src/mark.rs.