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.
Authored by: tmaruyama 2011-09-12
Parent: [r7209]
Child: [r7211]
