The xversion-upgrade test fails to stop server

Hello Andrew,

While reviewing recent buildfarm failures, I came across this one:
https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=crake&dt=2024-05-23%2004%3A11%3A03

upgrade.crake/REL_16_STABLE/REL9_5_STABLE-ctl4.log
waiting for server to shut 

down...........................................................................................................................

failed
pg_ctl: server does not shut down

Looking at:
https://github.com/PGBuildFarm/client-code/blob/05014d50e/PGBuild/Modules/TestUpgradeXversion.pm#L641

I see that ctl4.log is created after updating extensions and
REL9_5_STABLE-update_extensions.log contains:
You are now connected to database "contrib_regression_redis_fdw" as user "buildfarm".
ALTER EXTENSION "hstore" UPDATE;
ALTER EXTENSION
You are now connected to database "contrib_regression_btree_gin" as user "buildfarm".
ALTER EXTENSION "btree_gin" UPDATE;
ALTER EXTENSION
...
but I see no corresponding server log file containing these commands in the
failure log.

When running the same test locally, I find these in inst/upgrade_log.

Maybe uploading this log file too would help to understand what is the
cause of the failure...

Best regards,
Alexander