web client/vandelay: Upload appends to last queue if no queue name specified.

Running Evergreen 2.12.2, using the web client's batch upload (vandelay).

I used the "Evergreen MARC File Upload" interface to upload a small file to merge (they were existing records so I selected "merge on best match". But I forgot to specify the queue name. In the client, doing this had caused a new queue to be created with no name. But in the web interface, it appended this small new file to a previous batch upload (and automatically overlaid on best match, as I requested!)

As a result, a bunch of records were unnecessarily re-overlaid with the wrong bibsource.

I was using Chrome 62.0.3202.94