"PERL_USE_UNSAFE_INC"

        There is a new environment variable recognised by the perl
        interpreter. If this variable has the value 1 when the perl
        interpreter starts up, then "." will be automatically appended to
        @INC (except under tainting).

        This allows you restore the old perl interpreter behaviour on a
        case-by-case basis. But note that this is intended to be a temporary
        crutch, and this feature will likely be removed in some future perl
        version. It is currently set by the "cpan" utility and
        "Test::Harness" to ease installation of CPAN modules which have not
        been updated to handle the lack of dot. Once again, don't use this
        unless you are sure that this will not reintroduce any security
        concerns.