Fix external permissions link behavior

Steps to reproduce:

• Configure email notifications on the Nuxeo instance.
• As a poweruser, navigate to a File document.
• Click on the Permissions tab and click the New button on the PERMISSIONS ASSIGNED TO EXTERNAL USERS section.
• Enter an email address.
• Set the From date to today and the To date to tomorrow.
• Click on the Create button.
  => Notification email with link to document should be sent.
• Right-click on the link to copy the link address.

In Chrome:

• Open a private browser and paste the link.
  => Redirected to https://nightly-rainforest.nuxeo.com/nuxeo/ui/NUXEO_SERVER/nuxeo/ui/sw.js?ts=[some_token]#!/doc/default/[UUID] and some code is displayed (see attached screenshot).
• Open another tab in the same browser and paste the link again.
  => File loads as expected.

This time not reproduced in Firefox, Edge or Safari.