Ah, thanks. I've just taken a look at how the tasks are sequenced, and basically forever what we've done is run the upgrade
after checking the configuration status. That's because in every single version ever (up until GSS2), the configuration was done in the newly-imaged system by device drivers contained in the imaged system, and upgrading the client before checking the results thus made no sense.
In GSS2, the bulk of the configuration settings are actually applied in DOS by a program called GhConfig.exe, and the old post-configuration drivers never actually run any more (which ends up meaning that the old version of the client has no result from them to retrieve, which ends up in an error).
It's a subtle detail that we seem to have missed, but in GSS2 we should upgrade the client earlier in the task process after going into the imaged system.