Leading space on code block before the 3 back ticks breaks the code block rendering correctly.
This does not break in github so should not break in showdown.

Example Input:

 ```javascript
var test = test;
...

Broken Output:

 ```javascript
var test = test;
...

Expected Output:

var test = test;
...

Please let me know if you need more detail or examples. This happens frequently when our customers create their markdown files. They see that their code blocks work in github and then they are broken on conversion with showdown. It's confusing for them.

Thanks!