Use unit id for package key #2535

Job	Run time
cabal	3m 21s
cabal-doExactConfig	3m 17s
nix-build	3m 21s
runghc	17s
tests-benchmarks	18s
unit-tests	13s
build-extra-hackages	3m 14s
docs	4m 1s
hix	1m 2s
hydra-ifdLevel-0-and-1	17s
hydra-ifdLevel-2	17s
hydra-ifdLevel-3-and-ghc-8-10	17s
hydra-ifdLevel-3-and-ghc-9-2	14s
hydra-ifdLevel-3-and-not-ghc-8-10-or-9-2	13s
maintainer-scripts	20s
multi-target	52s
plan-extra-hackages	32s
shellFor-multiple-package	37s
shellFor-hoogle	37s
shellFor-not-depends	41s
shellFor-single-package	40s
check-materialization-concurrency	27s
check-path-support	19s
closure-size	10s
haskell-nix-roots-do-not-require-IFDs	11s
hix-cabal	23s
hydra-without-remote-builders-ghc8107	2m 43s
hydra-without-remote-builders-ghc9101	2m 31s
nix-tools	19s
update-docs	9s
	31m 53s

Provide feedback