spurious pg_amcheck test failure

Hi,

In a rare CI failure I just noticed:

https://cirrus-ci.com/task/4901437240508416

https://api.cirrus-ci.com/v1/artifact/task/4901437240508416/testrun/build/testrun/pg_amcheck/002_nonesuch/log/regress_log_002_nonesuch

[11:38:06.031](0.000s) #   Failed test 'schema exclusion pattern overrides all inclusion patterns stderr
/(?^:pg_amcheck:warning: skipping database "template1": amcheck is not installed)/'
 
#   at /Users/admin/pgsql/src/bin/pg_amcheck/t/002_nonesuch.pl line 400.
[11:38:06.031](0.000s) #                   'pg_amcheck: warning: skipping database "another_db": amcheck is not
installed
# '
#     doesn't match '(?^:pg_amcheck: warning: skipping database "template1": amcheck is not installed)'
[11:38:06.031](0.000s) not ok 107 - schema exclusion pattern overrides all inclusion patterns stderr /(?^:pg_amcheck:
error:no relations to check)/
 
[11:38:06.031](0.000s) #   Failed test 'schema exclusion pattern overrides all inclusion patterns stderr
/(?^:pg_amcheck:error: no relations to check)/'
 
#   at /Users/admin/pgsql/src/bin/pg_amcheck/t/002_nonesuch.pl line 400.
[11:38:06.031](0.000s) #                   'pg_amcheck: warning: skipping database "another_db": amcheck is not
installed
# '
#     doesn't match '(?^:pg_amcheck: error: no relations to check)'


I don't really understand how there can be an *occasional* reordering of the
database list - afaict the pg_amcheck query has an ORDER BY that should
prevent that?
    ") AS combined_records"
    "\nORDER BY pattern_id NULLS LAST, datname");

Greetings,

Andres Freund