Use unit id for package key #2495

Job	Run time
build-extra-hackages	1m 48s
cabal	1m 47s
docs	1m 15s
cabal-doExactConfig	1m 46s
hix	1m 16s
maintainer-scripts	23s
multi-target	23s
nix-build	19s
plan-extra-hackages	16s
runghc	15s
shellFor-hoogle	19s
shellFor-multiple-package	21s
shellFor-not-depends	14s
tests-benchmarks	17s
unit-tests	13s
shellFor-single-package	16s
check-materialization-concurrency	24s
check-path-support	11s
closure-size	7s
haskell-nix-roots-do-not-require-IFDs	8s
hydra-ifdLevel-0-and-1	59s
hydra-ifdLevel-2	43s
hydra-ifdLevel-3-and-ghc-8-10	38s
hydra-ifdLevel-3-and-ghc-9-2	22s
hydra-ifdLevel-3-and-not-ghc-8-10-or-9-2	22s
update-docs	9s
hix-cabal	1m 38s
hydra-without-remote-builders-ghc8107	1m 35s
hydra-without-remote-builders-ghc9101	1m 23s
nix-tools	24s
	20m 11s

Provide feedback