Make sure the column_name is different from 'all'.

968c581e have fixed the EagerLoadTest, but
not in the correct way.

The problem was when `empty?` or `size` was called on relation. It was
triggering `count(:all)`, which was passing `:all` as the column name to `count`
on Calculations.

On the other hand, the method `calculate` on Calculations was calling
`construct_relation_for_association_calculations` instead of `perform_calculation`,
because `has_include?` was returning `true` since `column_name` was present.

To prevent calling the wrong method to perform the calculation, we have to check
if the `column_name` is present and if it is different from `:all` (which is now used
to correctly do `count` with `select`).

More information here: https://github.com/rails/rails/commit/968c581ea34b5236af14805e6a77913b1cb36238#commitcomment-6006135

activerecord/lib/active_record/relation/calculations.rb

@@ -188,7 +188,7 @@ def ids
     private
 
     def has_include?(column_name)
-      eager_loading? || (includes_values.present? && (column_name || references_eager_loaded_tables?))
+      eager_loading? || (includes_values.present? && ((column_name && column_name != :all) || references_eager_loaded_tables?))
     end
 
     def perform_calculation(operation, column_name, options = {})