add empty line after guard clause to app/models/issue_query.rb

git-svn-id: http://svn.redmine.org/redmine/trunk@20502 e93f8b46-1217-0410-a6f0-8f06a7374b81

app/models/issue_query.rb

@@ -222,6 +222,7 @@ class IssueQuery < Query
 
   def available_columns
     return @available_columns if @available_columns
+
     @available_columns = self.class.available_columns.dup
     @available_columns += issue_custom_fields.visible.collect {|cf| QueryCustomFieldColumn.new(cf)}