Ensure that paginate_by_sql doesn't change the original SQL query. Cl…

…oses mislav#235

lib/will_paginate/finder.rb

@@ -127,7 +127,7 @@ def paginated_each(options = {}, &block)
       # 
       def paginate_by_sql(sql, options)
         WillPaginate::Collection.create(*wp_parse_options(options)) do |pager|
-          query = sanitize_sql(sql)
+          query = sanitize_sql(sql.dup)
           original_query = query.dup
           # add limit, offset
           add_limit! query, :offset => pager.offset, :limit => pager.per_page

test/finder_test.rb

@@ -397,6 +397,15 @@ def test_paginating_finder_doesnt_mangle_options
       Developer.paginate(options)
       assert_equal options, options_before
     end
+
+    def test_paginate_by_sql_doesnt_change_original_query
+      query = 'SQL QUERY'
+      original_query = query.dup
+      Developer.expects(:find_by_sql).returns([])
+
+      Developer.paginate_by_sql query, :page => 1
+      assert_equal original_query, query
+    end
 
     def test_paginated_each
       collection = stub('collection', :size => 5, :empty? => false, :per_page => 5)