Incorrect content type set for uploaded files in Confluence through comment box

Steps to reproduce:

1. Go to any page, click on the 'Write comment...' box.
2. Dragged-in a file named, for example "testing_transition.patch" into the editor.
3. Go to the database, and run the following query:

   SELECT * FROM ATTACHMENTS;
   

4. It will show in the CONTENTTYPE column that the value is application/x-upload-data instead of text/plain. According with the from mime.types from Confluence, files .patch should be text/plain.

Example:

• As you can see in the picture below, the first two files was upload from the comment box, and the third file was uploaded through (Tools > Attachments).