This error happens because the column COMMIT_REVISION in the table USER_COMMIT is set to TEXT,

2011-10-24 12:06:05,071 ERROR [main] [SchemaUpdate] Unsuccessful: create index commit_rev_idx on USER_COMMIT (COMMIT_REVISION)
2011-10-24 12:06:05,071 ERROR [main] [SchemaUpdate] BLOB/TEXT column 'COMMIT_REVISION' used in key specification without a key length

There is a limitation on indexing TEXT type fields. As this post states, we can have VARCHAR type with maximum 65,532 bytes after MySQL 5.0.3.

We should change the column type from TEXT to VARCHAR.