Failure to move photos off the tablet with multi-step upload

[martinburchell]

To repeat:

• Invoke multi-step upload either through the server setting or by exceeding the database limit for one-step upload
• Complete a photo task for a patient
• Upload the photo task, selecting Keep patients and move

The upload fails with the error from the server:

Server reported an error: Must provide the variable: move_off_tablet_values

This happens because:

• move_off_tablet is NULL for the blob record associated with the photo.
• requestRecordwisePkPrune sends the which_keys_to_send request with move_off_tablet_values as an empty string.
• The server complains because which_keys_to_send is not set.

Workaround (for clinician mode) is to upload with copy before move. This will set the move_off_tablet flag on the records when they are copied so they will not be NULL when they are moved.