use includes instead of joins at Issue#visible...
use includes instead of joins at Issue#visible
"rake test" passes all test, but following test fails on command line.
<pre>
$ ruby test/unit/issue_test.rb -n test_visible_scope_for_member_with_groups_should_return_assigned_issues
1) Failure:
IssueTest#test_visible_scope_for_member_with_groups_should_return_assigned_issues [test/unit/issue_test.rb:321]:
Failed assertion, no message given.
</pre>
git-svn-id:
http://svn.redmine.org/redmine/trunk@13500 e93f8b46-1217-0410-a6f0-8f06a7374b81
