Redmine

To test redmine plugins, I also run redmine tests to verify the plugin doesn't screw things up.

But sometimes I get this Test Failure:

  1) Failure:
IssueImportTest#test_should_not_import_with_default_tracker_when_tracker_is_invalid [test/unit/issue_import_test.rb:89]:
"Tracker cannot be blank" not found in "Tracker doit être renseigné(e)
Statut doit être renseigné(e)" 

What I do is:

$ rake db:drop db:create db:migrate redmine:plugins:migrate RAILS_ENV=test REDMINE_LANG=en
....
$ rake redmine:load_default_data RAILS_ENV=test REDMINE_LANG=en
Default configuration data loaded.
$ rake test
....

I happens about once in three runs.
Redmine Version is 3.3.0.

Setting REDMINE_LANG for rake test doesn't help.

Any Ideas?