PubMed batch import fails on non valid PMID

When trying to import invalid PubMed id via the batch import at biblio/import, the import will go on for ever with no error message (unless you hit escape). I've hit this edge case because http://www.ncbi.nlm.nih.gov/pubmed/20966670 use to be a valid PMID, but not anymore.

The regular node/add/biblio will return a error fine though, but I thought that for consistency, the batch should do the same.