This was applied by generating a patch between MySQL 5.1.50 InnoDB plugin and the just-merged innodb+ from mysql-trunk revision-id: vasil.dimov@oracle.com-20100422110752-1zowoqxel5xx3z2e
Then, some manual merge resolving and it worked. This should make it much easier to merge the rest of InnoDB 1.1 and 1.2 from the mysql tree using my bzr-reapply script.