CI: cabal-testsuite tests fail with "double directory"

[ulysses4ever]

It was observed earlier on Windows:

• Hack around CI problems by sudo chown and disabling cache for Windows validate #8739

but since GHC 9.6.1 it plagues the other platforms too. Here's one recent CI run.

PackageTests/NewBuild/CmdRun/Terminate/cabal.test.hs:4:1: error:
Error:     Ambiguous module name ‘System.Directory’:
      it was found in multiple packages:
      directory-1.3.8.1 directory-1.3.8.1
  |
4 | import System.Directory (removeFile)
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Due to this error I had to disable cabal-testsuite altogether for 9.6.1 in #8840.

[Mikolaj]

High priority IMHO. Even if it's just that some tests are expected to trash the store, but they are not properly isolated, we need to weed them out. It can also be an actual bug. Either way, disabling our CI is a tragedy that will lead to other serious bugs introduced undetected.

[jgotoh]

I have this bug on my machine running with ghc 9.2.8 and cabal 3.10.1.0. Can I help you debug this somehow? Every test that imports System.Directory in the cabal-testsuite does not work for me

[Mikolaj]

@jgotoh: thank you very much. At some point @grayjay wanted to have a look at a log of a failed run (now provided in #8356), so I guess having a local reproducing checkout or hints about how to set up one could be valuable as well.

[ulysses4ever]

@Mikolaj should we close this on favor of #8356? I thought the title and description here is a little more clear, but you seem to be posting updates there. So, currently it's a bit confusing.

[Mikolaj]

I've now stolen your ticket title and description, so we can safely close this now. :)

[ulysses4ever]

Only good things get stolen, so I'm happy!