Message 66519 - Python tracker

This affects OS X too.

I'm attaching two patches - one uses malloc to build a bigger string if
the existing implementation returns ERANGE, and the other one uses
malloc from the start.  This was done on the theory that stack memory
use would be better/more efficient.  However, based on testing, there's
no real difference - 16.8usec vs. 17usec - on a rarely-used function.