Clicking markdown 'Preview' tab spawns two XHR requests
Summary
When someone wants to preview markdown when writing an issue, it is possible to click 'Preview' tab.
Clicking this tab triggers two asynchronous requests to load the processed markdown.
Expected behavior
Only one request should be generated.
Relevant logs and/or screenshots
![double_preview](data:image/gif;base64,R0lGODlhAQABAAAAACH5BAEKAAEALAAAAAABAAEAAAICTAEAOw==)