Loading perl module LWP::Simple causes seg fault

Question

I just ran pacman -Syu (upgraded 400 packages and the kernel went from 3.12.9-2 to 3.16.1-1 to give an idea of the last time I updated this system).
Now when I run:
perl -e 'use LWP::Simple'
It seg faults and dumps core.
pacman says: /usr/share/perl5/vendor_perl/LWP/Simple.pm is owned by perl-libwww 6.08-1 Which is the current version.  I tried reverting to 6.05-1 (the version I had previously) but it give the same result.
Checking pacman.log, I see two errors:
[2014-08-30 21:31] [PACMAN] installed perl-xml-sax-base (1.08-3)
[2014-08-30 21:31] [ALPM-SCRIPTLET] /tmp/alpm_TUIVDd/.INSTALL: line 1: 21528 Segmentation fault (core dumped) perl -MXML::SAX -e "XML::SAX->add_parser(q(XML::SAX::PurePerl))->save_parsers()" &> /dev/null
[2014-08-30 21:31] [PACMAN] installed perl-xml-sax (0.99-4)
[2014-08-30 21:31] [ALPM-SCRIPTLET] could not find ParserDetails.ini in /usr/share/perl5/vendor_perl/XML/SAX
So I uninstalled those packages and when I reinstalled, there were no errors... that didn't help.
Any ideas?

Answer 1

I found what's causing it, but still don't know how it got there.  For anyone else who has similar problems, here's how I found which module was the problem:
strace perl -e 'use LWP::Simple' |& grep '^open' | tail -1
In my case, it shows:
open("/usr/lib/perl5/site_perl/auto/Storable/Storable.so", O_RDONLY|O_CLOEXEC) = 5
I'm not sure why I have that file when I also have the proper /usr/lib/perl5/core_perl/auto/Storable/Storable.so.  Perhaps I was installing stuff from CPAN and it did that to fulfill a dependency?
And it's far from the only one:  I found 27 other .so duplicates in site_perl that are also in core_perl:
cd /usr/lib/perl5/site_perl
find . -name "*.so" | xargs -n1 pacman -Qo |& grep "No package owns" | cut -c24- | xargs -n1 -I{} ls -l ../core_perl/{} |& grep -v "cannot access"
Cleaning this up isn't going to be fun... I have 12 more .so's in site_perl that do NOT exist in core_perl or vendor_perl... so I can't just delete all unowned files in site_perl.