Use unit id for package key #2479

Job	Run time
cabal	2m 38s
cabal-doExactConfig	2m 37s
nix-build	49s
unit-tests	20s
build-extra-hackages	2m 36s
docs	3m 3s
hix	2m 52s
hydra-ifdLevel-2	1m 13s
hydra-ifdLevel-3-and-ghc-9-2	44s
hydra-ifdLevel-0-and-1	1m 52s
maintainer-scripts	43s
multi-target	36s
shellFor-hoogle	57s
plan-extra-hackages	22s
runghc	39s
shellFor-multiple-package	36s
shellFor-not-depends	27s
shellFor-single-package	28s
tests-benchmarks	26s
check-materialization-concurrency	21s
check-path-support	23s
closure-size	10s
haskell-nix-roots-do-not-require-IFDs	14s
hydra-ifdLevel-3-and-ghc-8-10	46s
hydra-ifdLevel-3-and-not-ghc-8-10-or-9-2	50s
hydra-without-remote-builders-ghc8107	1m 50s
hydra-without-remote-builders-ghc9101	1m 29s
nix-tools	1m 32s
update-docs	11s
hix-cabal	7m 1s
	38m 45s

Provide feedback