Cannot batch ingest PDF newspaper issues through Drush

I'm trying to batch ingest newspaper issues using PDFs, with this command:

drush -u 1 islandora_batch_scan_preprocess --content_models=islandora:newspaperIssueCModel --uri=https://bchdp.arcabc.ca{{ --type=directory --parent_relationship_pred=isMemberOf --target=/my/directory/stagedata/whiterock/semsun --parent=whiterock:1}}

I get an error: 
Datastream must have a datastream id. (foxml:datastream: value of ID is missing)
 

It seems like the Newspaper solution pack has a weird quirk, in that Newspaper Issues can only be ingested via the UI as PDFs, but they can only be ingested through Drush as TIFFs.

I would love for someone to prove me wrong and show me how I can make it work as-is, but I suspect the answer will require patching.