Is this a bug?

is there a way around it?

Install the prerequisites manually, then

cpan get Net::AS2
cpan look Net::AS2
[download]

Edit MakeFile.PL:

use ExtUtils::MakeMaker;
# See lib/ExtUtils/MakeMaker.pm for details of how to influence
# the contents of the Makefile that is written.
WriteMakefile(
    NAME            => 'Net::AS2',
    VERSION_FROM    => 'lib/Net/AS2.pm',
    PREREQ_PM       => {},
    ABSTRACT_FROM   => 'lib/Net/AS2.pm',
    AUTHOR          => 'Sam Wong <sam@hellosam.net>',
    PREREQ_PM       => {
        'Carp' => 0,
        'Crypt::SMIME' => 0,
        'LWP::UserAgent' => 0,
        'HTTP::Message' => 0,
        'Digest::SHA1' => 0,
        'MIME::Base64' => 0,
        'MIME::Tools' => 0,
    }
);

# install as normal
perl MakeFile.PL
make
make test 
make install
[download]

Feel free to raise a bug/provide a patch to fix this here.

Update: Ticket raised, patch provided.