Hi Howard,
to be able to "rebuild" relative links (at restore time) some extra info is generated inside the backup file (at backup time). This include processing *every* call to file.php and encoding them in a "special" format. Then, the restore process will be able to recode all the links again (including changing URLs like yours...).
But, obviously, the the "encode" task has to be executed prior to be able to "decode" it and it's only available since 2-3 weeks ago. So you need a 1.3beta backup file in order to restore it in 1.3beta (too!!) with all the "rebuild links" stuff working.
If your backup file version is 1.1 or .1.2 then links won't be processed!!
I think that this is your situation, because your "oldurl" to "newurl/moodle/test" is exactly the type of links being restored in 1.3.
Ciao