On FreeBSD 7.0 amd64, applying Mark's patch does get the test to pass.

As noted on python-dev, the response I got from the author of the new
malloc() package in FreeBSD 7.x indicates that as of 7.1 the allocator
defaults to using sbrk() rather than mmap() (strategy selection is
tunable with an environment variable) so the problematic behaviour
should be masked once 7.1 is released.

Martin: I'm missing something regarding your comment about the failure
message - the exception text seems literally correct (though not
particularly useful), though I haven't spent a lot of time trying to
understand how test_array works.  What would you suggest?