Clicking save instead of upload causes attaching to silently fail

On a story, click "Attach a file", then "Browse...", then pick a file. Then click "Save" (instead of "Upload"). This causes the attachment to be forgotten (never uploaded). Expected behavior would be for "Save" to cause the upload to happen or, perhaps, something like greying out save or some kind of error telling you to click upload or something. But the current behavior is confusing - it does not match what you'd expect based on what Save does for other fields.