| Subject: | shift on reference is experimental |
There's a new warning in newer perl versions (5.20.x, 5.21.x): "shift on reference is experimental". See http://www.cpantesters.org/cpan/report/203b8f80-a22a-11e4-931f-81ede0bfc7aa for a sample test report where this happens.
Also, the same usage prevents the successful run of the test suite on older perl versions (5.12.x and older). See http://matrix.cpantesters.org/?dist=Email-Assets for a pass/fail overview.