History of JobGroup::drop 1 change

In crates/flow/src/syscall.rs, lines 451–460 on ea56c56eaf90763e11badbeb8f43fc79d955b6be6c0fa800e7b8f69935877c30. 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 451,460:crates/flow/src/syscall.rs.