fix #delete_all with habtm with :delete_sql

Author: jonleighton

activerecord/lib/active_record/associations/has_and_belongs_to_many_association.rb

@@ -44,6 +44,7 @@ def count_records
 
         def delete_records(records, method)
           if sql = options[:delete_sql]
+            records = load_target if records == :all
             records.each { |record| owner.connection.delete(interpolate(sql, record)) }
           else
             relation  = join_table

activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb

@@ -379,6 +379,12 @@ def test_deleting_array_with_sql
     assert_equal 0, active_record.developers_by_sql(true).size
   end
 
+  def test_deleting_all_with_sql
+    project = Project.find(1)
+    project.developers_by_sql.delete_all
+    assert_equal 0, project.developers_by_sql.size
+  end
+
   def test_deleting_all
     david = Developer.find(1)
     david.projects.reload