+ my $force = $ENV{PERL_VARIABLE_MAGIC_TEST_THREADS} ? 1 : !1;
+ my $t_v = $force ? '0' : '1.67';
+ my $ts_v = $force ? '0' : '1.14';
+ skipall 'This perl wasn\'t built to support threads'
+ unless $Config{useithreads};
+ skipall 'perl 5.13.4 required to test thread safety'
+ unless $force or $] >= 5.013004;
+ skipall "threads $t_v required to test thread safety"
+ unless eval "use threads $t_v; 1";
+ skipall "threads::shared $ts_v required to test thread safety"
+ unless eval "use threads::shared $ts_v; 1";