Sequence alteration does not alter.

When the schema diff decides there are differences between the existing SEQUENCE and the "new" one it alters the SEQUENCE by a DROP and then a CREATE.

The CREATE is done with the fromSchema as a base which results in a no-changed SEQUENCE.

Line 102 in Doctrine/DBAL/Schema/Comparator.php uses fromSchema but shuld have been using toSchema or just $sequence

This will fix the immediate issue but still require the sequence name being the same.