[PATCH] gitlab: purge msys pacman cache

["Daniel P. Berrangé" <berrange@redhat.com>]

For the Windows msys2 CI job we install many packages using pacman
and use the GitLab cache to preserve the pacman cache across CI
runs. While metadata still needs downloading, this avoids pacman
re-downloading packages from msys2 if they have not changed.

The problem is that pacman never automatically purges anything
from its package cache. Thus the GitLab cache is growing without
bound and packing/unpacking the cache is consuming an increasing
amount of time in the CI job.

If we run 'pacman -Sc' /after/ installing our desired package set,
it will purge any cached downloaded packages that are not matching
any installed package.

This will (currently) cap the pacman download cache at approx
256 MB.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
---
 .gitlab-ci.d/windows.yml | 1 +
 1 file changed, 1 insertion(+)

See a test job with this change, plus a find across the msys
pacman cache, showing the cleanup effects....

Before cleanup:

  https://gitlab.com/berrange/qemu/-/jobs/11679136531#L34

After cleanup:

  https://gitlab.com/berrange/qemu/-/jobs/11679136531#L1126

diff --git a/.gitlab-ci.d/windows.yml b/.gitlab-ci.d/windows.yml
index 1e6a01bd9a..6e1135d8b8 100644
--- a/.gitlab-ci.d/windows.yml
+++ b/.gitlab-ci.d/windows.yml
@@ -87,6 +87,7 @@ msys2-64bit:
       mingw-w64-x86_64-pkgconf
       mingw-w64-x86_64-python
       mingw-w64-x86_64-zstd"
+  - .\msys64\usr\bin\bash -lc "pacman -Sc --noconfirm"
   - Write-Output "Running build at $(Get-Date -Format u)"
   - $env:JOBS = $(.\msys64\usr\bin\bash -lc nproc)
   - $env:CHERE_INVOKING = 'yes'  # Preserve the current working directory
-- 
2.50.1