History of CasFs::readlink 1 change

In crates/flow-casfs/src/main.rs, lines 219–224 on 78c45d1a752eaa2795476616969840a77f83d9708ed0326af0c09e4f334294ba. 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 219,224:crates/flow-casfs/src/main.rs.