History of propagate 2 changes

In crates/hub/src/diffusion.rs, lines 851–853 on addec2bd64233dc417bc7fe3def21815b5960fcb4381bd5d35a8fc2db07594f3. 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 851,853:crates/hub/src/diffusion.rs.