[mythtv-users] Error upgrading DB scheme from .20.2 to 21

[Brent Norris]

When mythbackend attempts to upgrade the DB on my friends mythtv install 
  it fails with the following error:

2008-05-20 15:18:04.443 DB Error (Performing database upgrade):
Query was: INSERT storagegroup (groupname, hostname, dirname)     SELECT 
DISTINCT 'Default', hostname, data     FROM settings     WHERE value = 
'RecordFilePrefix'         AND hostname IS NOT NULL         AND hostname 
<> '';
Error was: Driver error was [2/1062]:
QMYSQL3: Unable to execute query
Database error was:
Duplicate entry 'Default-mythback-/storage' for key 2

new version: 1171
2008-05-20 15:18:04.445 Database Schema upgrade FAILED, unlocking.
2008-05-20 15:18:04.446 Couldn't upgrade database to new schema


Logging into mysql and running the query results in:

mysql> select DISTINCT  'Default', 'mythback', '/storage' from settings;
+---------+----------+----------+
| Default | mythback | /storage |
+---------+----------+----------+
| Default | mythback | /storage |
+---------+----------+----------+
1 row in set (0.00 sec)

It looks to me like this duplicate entry is the problem, what do i need 
to do to get rid of it, so that the upgrade can complete?

Thanks

Brent