Created attachment 442004 [details] logfile for 'g-cpan -iv Math-GSL' until ^C 'g-cpan -iv Math-GSL' fails. It generates an endless loop creating a new 'Build' script for 'Module-Build' version '0.4218', see the attachment. BTW., dev-perl/Module-Build-0.421.600 is already installed. Why 'g-cpan -iv Math-GSL' wants to install perl-gcpan/Module-Build?
Could you please specify version? Is it still reproducible on last version (0.16.9)?
I'm hitting the same problem (except that Module-Build is now version 0.4224). This is version 0.16.9.
Checked with g-cpan-0.17.0 (will be in portage shortly). Math-GSL-0.40.ebuild was created without any issue. Please check it on your side.
Please check with v0.17.0