Rails3: scm: mercurial: fix error of test_show_tag at functional test

On Rails 3.1, ActiveRecord::HasManyThroughCantAssociateThroughHasOneOrManyReflection error raises.
For more details, see r7062.

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@7210 e93f8b46-1217-0410-a6f0-8f06a7374b81

test/functional/repositories_mercurial_controller_test.rb

@@ -181,8 +181,10 @@ class RepositoriesMercurialControllerTest < ActionController::TestCase
     end
 
     def test_show_tag
+      assert_equal 0, @repository.changesets.count
       @repository.fetch_changesets
-      @repository.reload
+      @project.reload
+      assert_equal NUM_REV, @repository.changesets.count
        [
         @tag_char_1,
         'tag_test.00',