Non-image attachments in comment notifications redirects to portal login

Summary

Any attachments (other than images) in notification email redirects to portal when clicked.

Steps to reproduce

1. Attach file to an issue
2. Send a comment including the link., [^example.txt].
3. Check notification e-mail and click on the link provided

Expected behavior

Clicking on the attachment link should trigger a download of the file.

Current behavior

Attachment link triggers a redirection to the customer portal instead of direct access.