Bug#690571: Tainted variable causes wrong smart matching in given/when constructs

[Christoph Nodes]

an even more reduced test would be

$ X=1 perl -Te 'print "smart match\n" if $ENV{X} ~~ [0, 1]'
$

compared to

$ X=1 perl -e 'print "smart match\n" if $ENV{X} ~~ [0, 1]'
smart match
$

-- 
Christoph