Mark, your patch will probably get the test to pass, but the underlying
reason the test is failing appears to be unexpected behaviour of the
platform malloc().

FreeBSD 7.0 introduced a new malloc() implementation that relies on
mmap() and this is behaving differently to the malloc() implementation
in FreeBSD 6.3 which relied on sbrk().

I have posted a query about the new malloc()'s behaviour to a FreeBSD
forum and will report what I find out.