Rust

`sha` is optional in `DiffEntry` if file contents are unchanged #1601

Job	Run time
wasm-build	50s
build (stable, ubuntu)	4m 1s
clippy	1m 11s
build (stable, ubuntu, -F stream)	3m 56s
build (stable, macos)	2m 55s
build (stable, macos, -F stream)	3m 0s
build (stable, windows)	8m 37s
build (stable, windows, -F stream)	8m 34s
build (beta, ubuntu)	4m 2s
build (beta, ubuntu, -F stream)	3m 52s
build (beta, macos)	3m 25s
build (beta, macos, -F stream)	2m 57s
build (beta, windows)	7m 16s
build (beta, windows, -F stream)	7m 14s
build (nightly, ubuntu)	2m 57s
build (nightly, ubuntu, -F stream)	3m 5s
build (nightly, macos)	2m 53s
build (nightly, macos, -F stream)	2m 52s
build (nightly, windows)	7m 22s
build (nightly, windows, -F stream)	7m 15s
	1h 28m 14s

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