Associativity of Join, and lots more #1593

Job	Run time
build (supported)	3m 45s
build (latest)	4m 18s
build (dev, --warnings)	5m 2s
nix	4m 11s
quick-build (supported, ubuntu-latest)	3m 27s
quick-build (latest, ubuntu-latest)	3m 25s
quick-build (dev, ubuntu-latest)	3m 18s
opam-build (supported, ubuntu-latest)	5m 11s
opam-build (8.17, ubuntu-latest)	6m 11s
opam-build (latest, ubuntu-latest)	6m 18s
opam-build (dev, ubuntu-latest)	7m 11s
doc-alectryon	14m 49s
doc-dep-graphs	9m 13s
doc-coqdoc	1m 6s
doc-timing	1m 25s
coqchk (supported)	2m 9s
install (supported)	1m 18s
coqchk (latest)	1m 45s
install (latest)	1m 17s
coqchk (dev)	2m 9s
install (dev)	1m 30s
deploy-doc	0s
delete-artifacts	4s
	1h 29m 2s

Provide feedback