Merge pull request #2047 from JasonGross/directives #984

Job	Run time
install (dev, Ubuntu, ubuntu-latest, 4.09.1)	39m 33s
install (dev, macOS, macos-latest, 4.14.2)	49m 2s
install (8.20.0, Ubuntu, ubuntu-latest, 4.09.1)	39m 27s
install (8.19.0, Windows, windows-latest, 4.13.1, -async-proofs-j 1, git+https://github.com/ocaml...	1h 35m 36s
install (8.19.0, macOS, macos-latest, 4.14.2)	42s
install (dev, Windows, windows-latest, 4.13.1, -async-proofs-j 1, git+https://github.com/ocaml/oc...	1h 33m 17s
install (8.20.0, macOS, macos-latest, 4.14.2)	45m 51s
install (8.18.0, Windows, windows-latest, 4.13.1, -async-proofs-j 1, git+https://github.com/ocaml...	1h 39m 55s
install (8.18.0, macOS, macos-latest, 4.14.2)	50s
install (8.18.0, Ubuntu, ubuntu-latest, 4.09.1)	42m 28s
install (8.20.0, Windows, windows-latest, 4.13.1, -async-proofs-j 1, git+https://github.com/ocaml...	1h 32m 31s
install (8.19.0, Ubuntu, ubuntu-latest, 4.09.1)	40m 11s
	10h 39m 23s

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