Subject: | Literal { in pattern deprecation will be fatal in 5.26.0 |
As of Perl 5.21.3 thus 5.22.0, literals such as { must be escaped in m// patterns.
https://metacpan.org/pod/release/PCM/perl-5.21.3/pod/perl5211delta.pod#A-literal-should-now-be-escaped-in-a-pattern
As of Perl 5.25.1 (currently pre-release but CPANTS alerted already!) thus future 5.26.0) the deprecated form is fatal. This will be Critical if not fixed before 5.26 release in fall 2016.
ref http://www.cpantesters.org/cpan/report/fd759eec-1798-11e6-ad9a-68c49ae6fa17