build

protect against SANY race conditions on the filesystem #7125

Job	Run time
build-mdbook	5s
scaladoc-check	3m 10s
integration-tests (ubuntu-latest, oopsla19)	19m 35s
format-check	3m 50s
integration-tests (ubuntu-latest, arrays)	8m 50s
unit-tests (ubuntu-latest)	5m 57s
integration-tests (macos-latest, oopsla19)	16m 9s
compiler-warnings	2m 2s
unit-tests (macos-latest)	3m 28s
docker-tests	21m 33s
	1h 24m 39s

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