Thanks.
It looks that my Scalar::Util is broken somehow. Since there is no .packlist file for Scalar I removed:

rm -rf ./5.8.8/i586-linux-thread-multi/Scalar ./5.8.8/Scalar

install Scalar::Util<br> worked fine.
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with

cpan> install CGI::Application::Plugin::Authentication
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I get the same error as on Debian:

t/02_config.................ok 1/69
#   Failed test 'config dies when RENDER_LOGIN is passed a hashref'
#   at t/02_config.t line 93.
# expecting: Regexp ((?-xism:parameter RENDER_LOGIN is not a coderef))
# found: Bizarre copy of ARRAY in sassign at /usr/lib/perl5/5.8.8/Carp
+/Heavy.pm line 45.
t/02_config.................NOK 31# Looks like you failed 1 test of 69
+.
t/02_config.................dubious
        Test returned status 1 (wstat 256, 0x100)
DIED. FAILED test 31
        Failed 1/69 tests, 98.55% okay
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Is this a bug?