Merge pull request rails#50859 from rails/no-row-mutation

Don't mutate row arrays that come back from the database adapter

Author: tenderlove

activerecord/test/cases/finder_test.rb

@@ -1614,9 +1614,9 @@ def test_select_rows
       [["1", "1", nil, "37signals"],
        ["2", "1", "2", "Summit"],
        ["3", "1", "1", "Microsoft"]],
-      Company.connection.select_rows("SELECT id, firm_id, client_of, name FROM companies WHERE id IN (1,2,3) ORDER BY id").map! { |i| i.map! { |j| j.to_s unless j.nil? } })
+      Company.connection.select_rows("SELECT id, firm_id, client_of, name FROM companies WHERE id IN (1,2,3) ORDER BY id").map { |i| i.map { |j| j.to_s unless j.nil? } })
     assert_equal [["1", "37signals"], ["2", "Summit"], ["3", "Microsoft"]],
-      Company.connection.select_rows("SELECT id, name FROM companies WHERE id IN (1,2,3) ORDER BY id").map! { |i| i.map! { |j| j.to_s unless j.nil? } }
+      Company.connection.select_rows("SELECT id, name FROM companies WHERE id IN (1,2,3) ORDER BY id").map { |i| i.map { |j| j.to_s unless j.nil? } }
   end
 
   def test_find_with_order_on_included_associations_with_construct_finder_sql_for_association_limiting_and_is_distinct