…reas J. Koenig's CPANtesters machines
RT66882 is an interesting bug. A single special function test fails due to loss of precision, only when DUSELONGDOUBLE is defined in Perl. It seems to have the same behavior across a wide number of Perl versions, from 5.6 to 5.13.x. Why are long doubles causing this loss of precision? Haven't the slightest, currently. It could be a bug in Perl 5, GSL or Math::GSL. It's a bug hunt.