Fix sync hang #5489

Job	Run time
Run doc tests	1m 41s
Reject trailing whitespace	4s
cargo-checkmate / Cache checkmate	8s
test / Build test artifacts	6m 31s
cargo-checkmate / Cargo checkmate (build)	2m 51s
cargo-checkmate / Cargo checkmate (check)	1m 48s
cargo-checkmate / Cargo checkmate (clippy)	2m 8s
cargo-checkmate / Cargo checkmate (doc)	2m 55s
cargo-checkmate / Cargo checkmate (format)	1m 0s
test / Run tests (1)	1m 18s
test / Run tests (2)	1m 22s
test / Run tests (3)	1m 20s
test / Run tests (4)	1m 22s
test / Run tests (5)	1m 21s
test / Run tests (6)	1m 15s
test / Run tests (7)	1m 22s
test / Run tests (8)	1m 22s
	29m 48s

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