I checked buildd log of qdbm and noticed that many architectures are failed to be built.

I looked into the log and found that it tried to install perl modules in wrong directory, such as ./debian/libqdbm-perl/build/buildd/perl-5.8.7/debian/tmp/usr/lib/perl5

Hmm, it seems perl ships wrong value in Config package. It was already reported as Bug#312419 and fixed in 5.8.7-3.

I hope all buildd update perl to 5.8.7-3, since most perl packages couldn't be bulit with perl 5.8.7-2.