Ah I see. For some reason CPAN installed Module::Build inside /home/andy/perl5/lib/perl5/site_perl. That is not there in @INC though....

What can I do next?

Edit: I tried to manually install Module::Build into ~/perl5. I used

perl Makefile.PL PREFIX=/home/andy/perl5/ 
make
make test
make install
[download]

Now my Module::Build went inside /home/andy/perl5/share/perl/5.8.8/.