event --slow-sync gets utterly confused

[madduck]

When synchronising events between a SyncML client (Nokia N900) and file-sync, a slow-sync utterly confuses osynctool. Note in the following how the normal sync is just fine, but the subsequent slow-sync dies with a useless error:

% osynctool --sync n900
Synchronizing group "n900" 
event sink of member 2 of type file-sync just connected
Main sink of member 2 of type file-sync just connected
Main sink of member 1 of type syncml-obex-client just connected
event sink of member 1 of type syncml-obex-client just connected
All clients connected or error
Main sink of member 1 of type syncml-obex-client just sent all changes
event sink of member 2 of type file-sync just sent all changes
Main sink of member 2 of type file-sync just sent all changes
event sink of member 1 of type syncml-obex-client just sent all changes
All clients sent changes or error
All changes got mapped
All conflicts have been reported
All changes got multiplied
All changes got prepared for write

Synchronization Forecast Summary:

ObjType: event
  Member 1: Adding(0) Modifying(0) Deleting(0)
  Member 2: Adding(0) Modifying(0) Deleting(0)

No modifications of any Member. Continuing.
Main sink of member 1 of type syncml-obex-client committed all changes.
event sink of member 2 of type file-sync committed all changes.
Main sink of member 2 of type file-sync committed all changes.
event sink of member 1 of type syncml-obex-client committed all changes.
All clients have written
event sink of member 1 of type syncml-obex-client reported sync done.
Main sink of member 1 of type syncml-obex-client reported sync done.
event sink of member 2 of type file-sync reported sync done.
Main sink of member 2 of type file-sync reported sync done.
All clients reported sync done
The sync was successful
event sink of member 1 of type syncml-obex-client just disconnected
Main sink of member 1 of type syncml-obex-client just disconnected
event sink of member 2 of type file-sync just disconnected
Main sink of member 2 of type file-sync just disconnected
All clients have disconnected



% osynctool --sync n900 --slow-sync event
Synchronizing group "n900" [slow sync]
event sink of member 2 of type file-sync just connected
Main sink of member 2 of type file-sync just connected
Main sink of member 1 of type syncml-obex-client just connected
event sink of member 1 of type syncml-obex-client just connected
All clients connected or error
Main sink of member 1 of type syncml-obex-client just sent all changes
Received an entry 72 (xmlformat-event) from member 2 (file-sync). Changetype ADDED
Received an entry 71 (xmlformat-event) from member 2 (file-sync). Changetype ADDED
event sink of member 2 of type file-sync just sent all changes
Main sink of member 2 of type file-sync just sent all changes
Received an entry 72 (xmlformat-event) from member 1 (syncml-obex-client). Changetype ADDED
Received an entry 73 (xmlformat-event) from member 1 (syncml-obex-client). Changetype ADDED
event sink of member 1 of type syncml-obex-client just sent all changes
All clients sent changes or error
All changes got mapped
All conflicts have been reported
All changes got multiplied
The sync failed: At least one object engine failed while preparing the write event. Aborting
event sink of member 1 of type syncml-obex-client just disconnected
event sink of member 2 of type file-sync just disconnected
Main sink of member 2 of type file-sync just disconnected
Main sink of member 1 of type syncml-obex-client just disconnected
All clients have disconnected
ERROR: At least one object engine failed while preparing the write event. Aborting