DMD needs branches

[Walter Bright]

Russell Lewis wrote:
> But that is not necessary the fault of the library code themselves. 
> Perhaps one of them can't use an old compiler because there is a 
> compiler crash, and one can't use a new compiler because it uses a 
> syntax (or keyword) that used to be valid but is now not allowed.  If 
> there was "stable" branch of the older compiler, that included the 
> bugfix but not the language change, then both libraries would work 
> together just fine.

But bugfixes themselves can cause such problems.