Fix for bug 72721 (duplicates.cgi performs poorly with lots of bugs) and bug 69054 (DB_File not portable): dependence on DB_File removed, now uses AnyDBM_File which comes standard with Perl.  Duplicates.cgi now runs its queries against the shadow database if it's available, among many other improvements.
Patch by gervase.markham@univ.ox.ac.uk (Gervase Markham)
r= justdave