Output of std.format for float difference between DMD and GDC

[BoraxMan via D.gnu]

I have noted that DMD and GDC provide a different output to the 
following line of code.

writeln(format("$%-12,3.2f",66543.22));
DMD outputs

$66,543.22

GDC outputs

$66,543.22 ,

As you can see, GDC puts a superflous comma at the end.  The goal 
of this line is to convert a float to a monetary representation, 
therefore DMD is what I want and GDC not.

The question is, is the line of code in error?  If not, does this 
mean there is a bug with GDC's libphobos?

Regards,
Dennis