Symfony default behaviour for handling reordering in collection type is wrong.

When you reorder to items saved in database as:

id: 56, name: first, order: 0
id: 57, name: second, order: 1

After changing they positions I receive:

id: 56, name: second, order: 0
id: 57, name: first, order: 1

Instead of:

id: 56, name: first, order: 1
id: 57, name: second, order: 0

Last occurrence at version 2.0.15