Description of problem:
Error: Package: 12:dhcp-4.2.1-0.2.b1.fc15.i686 (rawhide)
          Requires: perl(Win32API::Registry) >= 0.21

Version-Release number of selected component (if applicable):
dhcp-4.2.1-0.2.b1.fc15.i686

How reproducible:
yum update

Steps to Reproduce:
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Actual results:
New rpm scans requirement differently. So, there's bug in rpm or in your specfile. 
You have in specfile, this:
%filter_requires_in %{_docdir}
%filter_setup

You can try add the line belove, but it should be already filtered by previous macro, because you install this file into docdir.
%filter_requires_in {path}dhcp-4.2.1b1/contrib/ms2isc/Registry.pm

Expected results:


Additional info: