As was discovered while testing MDL-46269, the tool_httpsreplace does not find URLs for images embedded via Mardown syntax -
https://daringfireball.net/projects/markdown/syntax#img

This issue is to decide if the tool should support this syntax too and eventually to track the development of such support.

Even though I am Markdown user, I don't personally think we need to support it in the HTTPS replace tool. It is really very rare / edge case.