start could be a string

Related to 761bc751 and
eb876c4d

activerecord/lib/active_record/relation/batches.rb

@@ -62,7 +62,7 @@ def find_in_batches(options = {})
         ActiveRecord::Base.logger.warn("Scoped order and limit are ignored, it's forced to be batch order and batch size")
       end
 
-      start = options.delete(:start).to_i
+      start = options.delete(:start) || 0
       batch_size = options.delete(:batch_size) || 1000
 
       relation = relation.reorder(batch_order).limit(batch_size)

activerecord/test/cases/batches_test.rb

@@ -128,14 +128,14 @@ def test_find_in_batches_should_use_any_column_as_primary_key
     old_primary_key  = Post.primary_key
     Post.primary_key = :title
     title_order_posts = Post.order('title asc')
-    start_title = title_order_posts.first.title
+    start_title = title_order_posts.second.title
 
     posts = []
     Post.find_in_batches(:batch_size => 1, :start => start_title) do |batch|
       posts.concat(batch)
     end
 
-    assert_equal title_order_posts.map(&:id), posts.map(&:id)
+    assert_equal title_order_posts[1..-1].map(&:id), posts.map(&:id)
   ensure
     Post.primary_key = old_primary_key
   end