History of JobGroup::drop 1 change

In crates/flow/src/syscall.rs, lines 428–437 on 8a4f5174526a58cc31b020871e52b8ff84f7fc3f5a2b544ff7b65db27c997a89. 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 428,437:crates/flow/src/syscall.rs.