cbbackup cannot use the backup directory made by the older release(2.5)

Steps to reproduce:

• Install older release: 2.5.1-1094-rel
• Created 80K items
• run cbbackup http://localhost /tmp/backup
• Uninstall the old release and
• Install new release (3.0.0-866)
• cbrestore data from the old dir structure
• Verify and ensure all data is restored
• Add/update items
• run cbbackup and supply the same directory used before:
  cbbackup http://localhost /tmp/backup

cbbackup throws error:

[root@centos-64-x64 tmp]# /opt/couchbase/bin/cbbackup http://Administrator:password@172.23.106.72:8091 /tmp/b100
2014-06-24 18:23:26,234: s0 error: async operation: error: unexpected db user version: 2004 vs [0] on sink: /tmp/b100(bucket0@172.23.106.72:8091)
error: unexpected db user version: 2004 vs [0]

expectation: cbbackuk should be able to use the old dir structure.