rails/rails — pull request #14838 by crismali (2014-04-22 14:49:13+00:00)
Title: Made PostgreSQLAdapter::SchemaCreation#columns_for_distinct iterate once, not 4 times

Made `PostgreSQLAdapter::SchemaCreation#columns_for_distinct` iterate once, instead of
4 times by using `Enumerable#each_with_object` with the same amount of conditionals.