process 1.6.13 behaviour change

This demonstrates the behaviour change in the process library from 1.6.13 onwards.

Run as follows:

$ make all CABAL=$(which cabal) GHC=$(which ghc)

tested with

$ ghc --version
The Glorious Glasgow Haskell Compilation System, version 8.10.7

$ cabal --version
cabal-install version 3.6.2.0
compiled using version 3.6.2.0 of the Cabal librar