Idempotent ring elements #2938

Job	Run time
build (supported)	3m 31s
build (latest)	3m 23s
nix	2m 9s
opam-build (supported, ubuntu-latest)	4m 51s
build (dev, --warnings)	3m 14s
quick-build (supported, ubuntu-latest)	3m 13s
opam-build (latest, ubuntu-latest)	4m 45s
quick-build (latest, ubuntu-latest)	3m 10s
opam-build (dev, ubuntu-latest)	4m 27s
quick-build (dev, ubuntu-latest)	3m 12s
doc-dep-graphs	7m 32s
doc-timing	1m 41s
doc-alectryon	15m 5s
doc-coqdoc	1m 40s
coqchk (supported)	1m 58s
coqchk (latest)	2m 6s
coqchk (dev)	1m 53s
install (supported)	1m 33s
install (latest)	1m 41s
install (dev)	1m 47s
deploy-doc	0s
delete-artifacts	10s
	1h 13m 1s

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