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.

Reproduce the issue by adding an image through drag-and-drop or the imgur upload button, then undo after the upload finishes. Trace the JavaScript handling for the upload placeholder and undo behavior; done means undo no longer restores the `![Uploading file..._random]()` text.

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