removeReferencesToVendoredSourcesHook: avoid using /dev/fd directly #1268

Job	Run time
examples-darwin	9m 2s
check-dead-code	22s
examples-linux (alt-registry)	3m 12s
tests (https://releases.nixos.org/nix/nix-2.18.2/install)	4m 35s
examples-linux (build-std)	5m 23s
check-fmt	37s
tests (https://releases.nixos.org/nix/nix-2.18.2/install, --override-input nixpkgs $(./ci/ref-fro...	4m 34s
examples-linux (cross-musl)	1m 47s
examples-linux (cross-rust-overlay)	2m 1s
examples-linux (cross-windows)	1m 36s
examples-linux (custom-toolchain)	1m 44s
examples-linux (end-to-end-testing)	4m 11s
examples-linux (quick-start)	1m 46s
examples-linux (quick-start-simple)	1m 45s
examples-linux (quick-start-workspace)	1m 55s
examples-linux (sqlx)	4m 34s
examples-linux (trunk-workspace)	2m 35s
examples-linux (trunk)	1m 54s
all systems go	0s
	53m 33s

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