In a multi-repository configuration, the 'pdf.js' preview is unable to retrieve the blob of the current document

How to reproduce:

• configure a multi-repository configuration as described in documentation Multiple+Repositories+Configuration (see attached ZIP file for a sample configuration template)
• navigate to the second repository
• create a File document with a PDF file
• click on the preview button in the Summary tab next to the blob's URL

The previewer does not find the blob as the URL is missing the repo/<repo_name> part.