Upgrade to 3.6.6 fails - Couldn't migrate printers tdb file

[Chris Smith]

>From the smbd.log level 10 log there is this:
=========================================
[2012/07/04 10:41:28.146531,  5, effective(0, 0), real(0, 0)]
printing/nt_printing_migrate_internal.c:54(rename_file_with_suffix)
  moved '/var/lib/samba/ntdrivers.tdb' to '/var/lib/samba/ntdrivers.tdb.bak'
[2012/07/04 10:41:28.146688,  3, effective(0, 0), real(0, 0)]
lib/charcnv.c:537(convert_string_talloc)
  convert_string_talloc: Conversion error: Illegal multibyte sequence(â0)
[2012/07/04 10:41:28.146750,  0, effective(0, 0), real(0, 0)]
lib/charcnv.c:543(convert_string_talloc)
  Conversion error: Illegal multibyte sequence(â0)
[2012/07/04 10:41:28.146823,  1, effective(0, 0), real(0, 0)]
../librpc/ndr/ndr.c:414(ndr_pull_error)
  ndr_pull_error(5): Bad character conversion with flags 0x42
[2012/07/04 10:41:28.146882,  2, effective(0, 0), real(0, 0)]
printing/nt_printing_migrate.c:207(printing_tdb_migrate_printer)
  printer pull failed: Character Conversion Error
[2012/07/04 10:41:28.146947,  0, effective(0, 0), real(0, 0)]
printing/nt_printing_migrate_internal.c:237(nt_printing_tdb_migrate)
  Couldn't migrate printers tdb file: NT_STATUS_NO_MEMORY
=========================================
Seems it doesn't like the ntdrivers.tdb file. It verifies fine with
tdbbackup and I can backup and restore with tdbbackup or
tdbdump/tdbrestore yet the same issue remains.