Fix for older versions of nixpkgs (#2326) #2964

Job	Run time
cabal	13s
build-extra-hackages	7s
cabal-doExactConfig	9s
check-materialization-concurrency	19s
closure-size	7s
check-path-support	5s
docs	24s
hix	32s
haskell-nix-roots-do-not-require-IFDs	16s
hix-cabal	7s
hydra-ifdLevel-0-and-1	2m 17s
hydra-ifdLevel-2	2m 22s
hydra-ifdLevel-3	18m 30s
hydra-without-remote-builders-ghc9101	34s
hydra-without-remote-builders-ghc966	36s
maintainer-scripts	7s
multi-target	28s
nix-build	35s
nix-tools	11s
plan-extra-hackages	6s
runghc	8s
shellFor-hoogle	10s
shellFor-multiple-package	18s
shellFor-not-depends	16s
shellFor-single-package	17s
tests-benchmarks	7s
unit-tests	5s
update-docs	4s
	29m 30s

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