Schema tool can throw errno 121 when creating or dropping indexes

When changing the model in such a way that the schema tool tries to create or drop an index which is also a foreign key an error is sometimes thrown like:

[PDOException]
SQLSTATE[HY000]: General error: 1025 Error on rename of '.\mydb#sql-10d8_19' to '.\mydb\auth' (errno: 121)

This seems to be caused by MySQL trying to re-use indexes and I think it depends on exactly what has happened before in this table so I can't give an exact case to reproduce. However, it seems to be InnoDB specific and I'm pretty sure its this bug: http://bugs.mysql.com/bug.php?id=15317