I have done some investigation, and found a .pem file <c>/root/cluster/local/lib/perl5/Mozilla/CA/cacert.pem<c> that appears to have a large number of root certificates concatenated together, and the SSL_ca_file() function in the Mozilla::CA module.

I tried converting my company root cert to .pem format and appending it to the end of cacert.pem file, but it did not fix the problem.

The cacert.pem file full of certificates is also inconsistent with the fact that my company root cert is accepted without any special configuration on other Ubuntu machines that are running system perl.