Problems with <> inside a <code>-block

Hello,

When I am posting some "tags" in my code-block(using full-html without limit html-tags), those tags will automatically closed.

For example, if I post inside my code-block:
<tab>

It will be automatically converted into:
<tab></tab>

If I post C-code like:
#include <stdio.h>

It gets converted to:

#include <stdio.h></stdio.h>

I don't want that ckeditor treats stuff inside the code-block like html-tags, since I want to display the code correctly.

The following line is commented out in my config.js:

// config.protectedSource.push(/<code>[\s\S]*?<\/code>/gi);

Does anybody know how to fix that?

BTW: I just figured out that the same problem exists in a plain new drupal8-installation