Looking at 28__chunklist doesn't seem to especially clear things up as to why things are going wrong

You'll get more verbose (and perhaps more meaningful) output if you run the test as:

perl -Mblib t/28__chunklist.t
[download]

Also, it will probably help if you insert some print statements into the test script that will enable you to see the values that are being obtained and causing the failure.

The same error is reported by one cpan tester at http://www.nntp.perl.org/group/perl.cpan.testers/2006/10/msg364997.html. Maybe you can work something out regarding the source of the problem by comparing what you both have in common (eg perl version, pre-requisites, etc.). The only Darwin builds reported as failing at http://cpantesters.perl.org/show/Bit-Vector.html#Bit-Vector-6.4 are for perl 5.8.6 - though that doesn't necessarily mean that perl 5.8.6 is the problem.

Cheers,
Rob