Use of uninitialized value in concatenation (.) or string at /usr/lib/perl5/5.8.8/i386-linux-thread-multi/Scalar/Util.pm line 30.

This error seems to crop up on Fedora-derived distributions after updates, and is apparently linked to a bug in the Scalar-Util module used by Fedora. The fix is to directly download the module from CPAN website and install it in place of the distribution module:

wget http://search.cpan.org/CPAN/authors/id/G/GB/GBARR/Scalar-List-Utils-1.19.tar.gz
tar xzvf Scalar-List-Utils-1.19.tar.gz

cd Scalar-List-Utils-1.19
perl Makefile.PL

make test
make install