D1 garbage collector + threads + malloc = garbage?

[Walter Bright]

Leandro Lucarella wrote:
> If you could add a small description of what the commit is about besides
> pointing the NG discussion/Bugzilla number, as you are doing with DMD now,
> it would be really great! =)

Just click on the link! (At least, that's how the changelog works.) 
Also, I added a comment in the source code that explains the why.