Attachment might be lost when fixing conflict

Reproduction steps:

• Go to Sandbox page and start editing it
• Remove the XWikiLogo.png image displayed in the content
• Using the wysiwyg editor capability upload the XWikiLogo.png image attached to that ticket and add it to the page where the old XWikiLogo.png was displayed
• Save the change as a new change request
• Go back on Sandbox page and delete the XWikiLogo.png image from the list of attachments
• Return to the Change request

Expected result:

• the created CR should display a conflict but the resolution of the conflict should be the addition of the new attachment

Obtained result:

• the created CR displays a conflict but the only resolution is leading to actually loosing the attachment info: the diff doesn't present any info regarding the new size and content of the attachment, and publishing the CR afterwards doesn't restore any attachment.