The following illustrates a markdown bug:
Proc := MyProc2;
Proc();//calls MyProc2
Editor screen shot:

The following illustrates a markdown bug:
Proc := MyProc2;
Proc();//calls MyProc2
Editor screen shot:

I don't know why you would put Unicode-magic space characters in there, but you can't really expect that to behave like a normal space. If you really think that you have to be able to use a U+00A0 in place of a regular ASCII space, that's a status-declined.
A code block has to be indented by four spaces or one tab, and I think it's pretty clear that "space" in that sentence means a plain good ol' ASCII 32. Since that's the largest key on my keyboard and thus the easiest way for me to insert a space, using any other kind of space means I am deliberately not inserting a regular space and hence expecting a different behavior.
This is notwithstanding the fact that there may currently be a bug in Chrome that erroneously inserts these characters. If that's the case and we're able to reproduce it, we'll try to work around it, but not by changing the semantics of Markdown.
I fixed a small preview/rendered version inconsistency that editing your post showed though; from the next build on, that'll be fixed: The server-rendered version will look like the preview – the first line is code, the second line isn't. That's the correct interpretation, since the first line starts with four spaces, the second one doesn't. So this part is a status-completed.
I'll let you choose which of the two tags you want.
Those are not ordinary spaces. Simple ASCII analysis of the exact string you wrote before the second line of code give the following result:

Here it is again to save the need to click "edit" on your post:
(Just copy the contents of this inline code block)
Can't copy this for some reason, to copy the source click "edit" on the question and copy the spaces before the second line of code.
How did you come up with those fancy characters in the first place? Anyway, it's not a bug since those characters are not plain spaces.