diff: impl Clone, Debug for DiffHunkIterator #15412

Job	Run time
Build jj-lib without Git support	44s
build (ubuntu-latest)	4m 47s
cargo-deny (advisories)	24s
Check that MkDocs can build the docs	21s
build (macos-13)	8m 49s
Check that MkDocs can build the docs with Poetry 1.8	20s
cargo-deny (bans licenses sources)	25s
build (macos-14)	3m 56s
Check formatting	20s
Clippy check	2m 31s
build (windows-latest)	10m 17s
build (ubuntu-latest, --all-features)	5m 43s
Check protos	31s
	39m 8s

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