[Duplicity-talk] Traversing already backed up files on restart

[Henrik Olsen]

When a backup job has been aborted midway, and then later restarted, why does 
duplicity traverse the files already backed up?

With verbosity 5 it reports

Last full backup left a partial set, restarting.
Last full backup date: Sat Mar 27 00:01:18 2010
Restarting after volume 144, file [path/to/where/duplicity/got/to], block 67

then continues to list/traverse all files already backed up, before continuing. 
It doesn't transfer anything, but seems to perhaps do checksum/signature checks 
on all the files. Why is this nessecary? I had hoped it would pick up directly 
from the volume it was stopped in.

Best regards
Henrik