<pre> element in Markdown - Doesn't work

[Gilbertdelyon]

Steps to reproduce:
Copy some text from a plain-text email (Thunderbird)
Paste it in Markdown editor (a post, a comment or a message).
And you will get this:

This is because in the plain-text email the text is embeded in a <pre> element.

Now if you paste the same <pre> element in the markdown editor of a custom page text element you will get this:

There it works !

It also works if I paste the same element in Github text editor.

So, the question is: Is this the normal behaviour of editor in post, comment and message? Or is it a bug?