When creating a page from a template, attached images are not displayed during editing

Steps to reproduce:

• Create a template with an attached image and insert that image into the page content (make sure to use a relative reference not including the template name).
• Create a template provider where "Action on create" is "Edit".
• Create a new page using the created template.
• Click on "Preview".
• Click on "Save".

Expected Results:

• The image is displayed in the WYSIWYG editor that is shown after clicking "Create" with the template selected.
• The image is displayed after clicking "Preview".

Actual Results:

• A broken image placeholder is displayed in CKEditor and after clicking "Preview".
• Only after clicking "Save", the image is correctly displayed.