install.hs is not idempotent with stack 2.1.1

[alanz]

Running ./install.hs build twice in a row with stack-2.1.1 installed instead of 1.9.3 results in certain targets being rebuilt.

[samuelpilz]

For me, stack itself is not idempotent.
The simple script triggers rebuilding of a lot of artifacts on my machine.

for f in stack*.yaml; do 
	echo "-- $f 1"
	stack build --stack-yaml $f
done

[samuelpilz]

See commercialhaskell/stack#4883 (comment) for my recent findings about this issue. This has nothing to do with hie or cabal-helper specifically.