cabal v2-exec fails to create environment.

[phadej]

[polinukli] /code/public-haskell/tree-diff master % cabal v2-exec env                       
Resolving dependencies...
/code/public-haskell/tree-diff/dist-newstyle/tmp/environment.-7050: createDirectory: does not exist (No such file or directory)

[polinukli] /code/public-haskell/tree-diff master % cabal --version
cabal-install version 3.0.1.0
compiled using version 3.0.1.0 of the Cabal library 

[polinukli] /code/public-haskell/tree-diff master % /opt/cabal/3.2/bin/cabal v2-exec env 
Resolving dependencies...
/code/public-haskell/tree-diff/dist-newstyle/tmp/environment.-7174: createDirectory: does not exist (No such file or directory)

[fgaz]

here the parent may not exist.
Solution: either we create it before calling withTempDirectory, or we modify withTempDirectory to do the equivalent of mkdir -p.
The first option is probably better. Look for other places where distTempDirectory is used to see how it's done

[phadej]

In other places the distTempDirectory is explicitly created before calling to withTempDirectory, I'll go with that.