nix-shell broken on master

[EggBaconAndSpam]

The salient bits: (full output)

[eggbaconandspam@fedora megaparsec]$ nix-shell
...
building '/nix/store/0jdakarnw4nhxa02drr8hbnpw5srqjky-megaparsec-9.2.2.drv'...
setupCompilerEnvironmentPhase
Build with /nix/store/w30rhw13ji6vkv0zksms5h7897cxvl90-ghc-8.8.4.
unpacking sources
unpacking source archive /nix/store/gghgh40ic1c9c6adp766mz0njxbf3v5q-source
source root is source
patching sources
compileBuildDriverPhase
setupCompileFlags: -package-db=/build/setup-package.conf.d -j8 +RTS -A64M -RTS -threaded -rtsopts
[1 of 1] Compiling Main             ( /nix/store/4mdp8nhyfddh7bllbi7xszz7k9955n79-Setup.hs, /build/Main.o )
Linking Setup ...
configuring
configureFlags: --verbose --prefix=/nix/store/lf7paq2abxpv61xgwl3mcv8zmln7x7hv-megaparsec-9.2.2 --libdir=$prefix/lib/$compiler --libsubdir=$abi/$libname --docdir=/nix/store/q3arlqiaad2cf2pcyhpnwiycd0f4jvw0-megaparsec-9.2.2-doc/share/doc/megaparsec-9.2.2 --with-gcc=gcc --package-db=/build/package.conf.d --ghc-options=-j8 +RTS -A64M -RTS --disable-split-objs --enable-library-profiling --profiling-detail=exported-functions --disable-profiling --enable-shared --disable-coverage --enable-static --disable-executable-dynamic --enable-tests --enable-benchmarks --enable-library-vanilla --disable-library-for-ghci --ghc-option=-split-sections --extra-lib-dirs=/nix/store/pk73wc0x32y2bmbiqiddb084w398ab6y-ncurses-6.2/lib --extra-lib-dirs=/nix/store/s0mblhs5vmjza9dmipn74rwqflxy1fw7-libffi-3.3/lib --extra-lib-dirs=/nix/store/fphpbj8jpyibz0l2xspidg6s7zm7xyb5-gmp-6.2.0/lib --extra-lib-dirs=/nix/store/w30rhw13ji6vkv0zksms5h7897cxvl90-ghc-8.8.4/lib
Using Parsec parser
Configuring megaparsec-9.2.2...
CallStack (from HasCallStack):
  die', called at libraries/Cabal/Cabal/Distribution/Simple/Configure.hs:1022:20 in Cabal-3.0.1.0:Distribution.Simple.Configure
  configureFinalizedPackage, called at libraries/Cabal/Cabal/Distribution/Simple/Configure.hs:475:12 in Cabal-3.0.1.0:Distribution.Simple.Configure
  configure, called at libraries/Cabal/Cabal/Distribution/Simple.hs:625:20 in Cabal-3.0.1.0:Distribution.Simple
  confHook, called at libraries/Cabal/Cabal/Distribution/Simple/UserHooks.hs:65:5 in Cabal-3.0.1.0:Distribution.Simple.UserHooks
  configureAction, called at libraries/Cabal/Cabal/Distribution/Simple.hs:180:19 in Cabal-3.0.1.0:Distribution.Simple
  defaultMainHelper, called at libraries/Cabal/Cabal/Distribution/Simple.hs:116:27 in Cabal-3.0.1.0:Distribution.Simple
  defaultMain, called at /nix/store/4mdp8nhyfddh7bllbi7xszz7k9955n79-Setup.hs:2:8 in main:Main
Setup: Encountered missing or private dependencies:
base >=4.15 && <5.0, scientific >=0.3.7 && <0.4

error: builder for '/nix/store/0jdakarnw4nhxa02drr8hbnpw5srqjky-megaparsec-9.2.2.drv' failed with exit code 1
error: 1 dependencies of derivation '/nix/store/krg9wnjsz9xa4kvp1q723630j8b7y6cy-ghc-8.8.4-with-packages.drv' failed to build