Just to finish our discussions on IRC... I found that mysql_client_test.test runs fine without any --plugin-dir=xxx option at all for mysql_client_test. The reason is that the correct option is in the my.cnf that we generate. So I decided to just remove the --plugin-dir option from the command line in mysql_client_test.test; this seems to work both when tested from source dir and when testing installed server. - Kristian.