Environment file from `cabal new-install ... --package-env .` has wrong store dir.

[fryguybob]

On Windows in my cabal/config I have store-dir: D:\cabal\store. When I run:

PS C: test-cabal> cabal --version
cabal-install version 2.4.1.0
compiled using version 2.4.1.0 of the Cabal library
PS C: test-cabal> cabal new-install ascii-cows --lib --package-env .
...

I get an environment file as expected, but with the wrong package-db entry:

PS C: test-cabal> cat .\.ghc.environment.x86_64-mingw32-8.6.4
clear-package-db
global-package-db
package-db C:\Users\Ryan.Yates\AppData\Roaming\cabal\store\ghc-8.6.4\package.db
package-id ghc-8.6.4
package-id bytestring-0.10.8.2
package-id base-4.12.0.0
package-id time-1.8.0.2
package-id hpc-0.6.0.3
package-id filepath-1.4.2.1
package-id process-1.6.5.0
package-id array-0.5.3.0
package-id integer-gmp-1.0.2.0
package-id containers-0.6.0.1
package-id ghc-boot-8.6.4
package-id binary-0.8.6.0
package-id ghc-prim-0.5.3
package-id ghci-8.6.4
package-id rts
package-id transformers-0.5.6.2
package-id deepseq-1.4.4.0
package-id ghc-boot-th-8.6.4
package-id pretty-1.1.3.6
package-id template-haskell-2.14.0.0
package-id directory-1.3.3.0
package-id text-1.2.3.1
package-id acme-dont-1.1-59f6208a892c7b15deee73943657a86fb76b00ee
PS C: test-cabal> ghci
GHCi, version 8.6.4: http://www.haskell.org/ghc/  :? for help
Loaded package environment from C:\Users\Ryan.Yates\Desktop\test-cabal\.ghc.environment.x86_64-mingw32-8.6.4
ghc.exe: can't find a package database at C:\Users\Ryan.Yates\AppData\Roaming\cabal\store\ghc-8.6.4\package.db

Fixing that line in the environment file to package-db D:\cabal\store\ghc-8.6.4\package.db and it works as expected.

[fgaz]

Pinging @typedrat