Attachments' behaviour in quotes

When you quote a message that has inserted attachments and then add your own attachments, they appear as if they have been inserted in the initially quoted message.

Steps to reproduce:

• type a message, add an attachment #1 and use the button 'Place inline';
• submit the message and quote it to create the next one;
• add an attachment #2 and submit the message.

Result: the attachment #2 is inserted in the quote.