Undo image upload results in "Uploading file..."

Adding an image to the document (either through drag-and-drop or through the imgur upload button) results in `![Uploading file..._random]()` being added to the document. After the upload is finished, this is replaced by the actual URL. Performing an undo action after successful upload shows the `![Uploading file..._random]()` text again. Ideally, this text should not be shown on undo.
