The default ubuntu version in travis ci has changed from trusty (14.04) to xenial (16.04), and xenial does not support old perls.
This PR sets dist: trusty explicitly for old perls.
Coverage decreased (-0.3%) to 97.5% when pulling f799d5ae00e26074dd244c6842b201dbf63b7501 on skaji:fix-travis into ce5405db4ec328df3249ac038d06d4392901a35e on fayland:master.
The default ubuntu version in travis ci has changed from trusty (14.04) to xenial (16.04), and xenial does not support old perls. This PR sets
dist: trusty
explicitly for old perls.See https://travis-ci.community/t/failure-with-perl-5-16-5-18-5-20/2458