Happy version downgrade

[Simon Peyton Jones]

Friends
I can't build ghc-9.0 because of this:

checking for ghc-pkg matching /opt/ghc/bin/ghc... /opt/ghc/bin/ghc-pkg

checking for happy... /home/simonpj/.cabal/bin/happy

checking for version of happy... 1.20.0

configure: error: Happy version 1.19 is required to compile GHC.
What is the easiest way to fix?  I have happy 1.19.8, but it's not called plain "happy"

bash$ happy-1.19.8 --version

Happy Version 1.19.8 Copyright (c) 1993-1996 Andy Gill, Simon Marlow (c) 1997-2005 Simon Marlow

Happy is a Yacc for Haskell, and comes with ABSOLUTELY NO WARRANTY.

This program is free software; you can redistribute it and/or modify

it under the terms given in the file 'LICENSE' distributed with

the Happy sources.
Thanks
Simon

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