Why doesn't URL appear in this question's rendered output?

Question

In the following question:

• How to make custom footer in page stick to bottom when the content is less?

The question text stops abruptly, which suggests something is missing:

You could find the code in source code in

If you go to "edit" the question then you can see there is a complete URL following the above text which also appears correctly in the rendered output from the editor.

However, this URL does not appear in the rendered output when viewing the question. It's not in the HTML source. Why not? Is there perhaps a hidden terminating character? Is it a "new user" restriction? Is it a bug?

(I've not tried editing/saving the question text - as I imagine this might resolve the issue.)

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As noted by @AndrewT. in comments, the issue seems to be caused by the capital "H" at the start of the URL:

• All lowercase URL : http://example.com/foo results in http://example.com/foo
• URL with a capital "H" : Http://example.com/foo results in
• All uppercase URL : HTTP://EXAMPLE.COM/FOO results in
• Mixed case URL : hTtp://eXampLE.COM/fOO results in
• Uppercase URL-path only : http://example.com/FOO results in http://example.com/FOO
• Lowercase protocol : http://EXAMPLE.COM/FOO results in http://EXAMPLE.COM/FOO
• Uppercase char in protocol : httP://example.com/foo results in

From these tests, it would seem that the scheme/protocol must be all lowercase to get recognised as a URL by the markdown parser. But this is only when viewing the rendered post; in the editor, the markdown preview shows all the URLs correctly hyperlinked. But the fact that the URL is completely removed from the rendered output would seem like a bug.