• Here's a failing run (and related branch is ihere: CI: add GHC 9.6.1 cabal#8840)

Not sure if it is related to the recent events like

• Fix #29: new input cabal-update: false to skip 'cabal update' #146
• Investigate why 'cabal update' hasn't run properly when setting up GHC 8.2 and cabal 2.4 #158?

The reason may be that we first haskell/setup (which does cabal update, which for cabal-3.10 uses XDG directories for storing config, store, etc.) and then restore cache with the legacy directory structure (under ~/.cabal). This confuses cabal.

Workaround: do cache-restore before haskell/setup. maybe not: to restore, you need to know the path that we usually got as an output of the action. So, pending more investigation.