Intermittent silent ghc-pkg.exe failures on windows-latest with GHC 9.2.8 #11585
Description
There is, sadly, nothing much to be said about it: the log shows ghc-pkg.exe being run with various subcommands, then the test runner reports Unexpected failure for <test>. Once it starts, it happens for all CI jobs for the next hour or so, then things return to normal.
It's probably not related to the recent switch of windows-latest to windows-2025, since there are both failing and succeeding runs on the new image (which went fully live on 2026-03-01). It has only happened with GHC 9.2.8, which does suggest there's some instability in that version that is somehow being triggered now but not earlier. It's also not a cache issue like the GLIBC/GLIBCXX symbol issue recently on Linux, since there have been failures since #11469 went in (see for example https://github.com/haskell/cabal/actions/runs/22730459904/job/65917786824#step:19:3870).