open qw(:std :utf8) not printed correctly at run time

[atoomic]

This is a simplified version of xtestc/2900.t

use open qw(:std :utf8);
BEGIN{ `echo -n ö > /tmp/xx.bak`; }
open X, "/tmp/xx.bak";
$_ = <X>;
print qq[ok $_\n] if ord($_) == 246;

This prints ok � instead of the expected ok ö the character is correctly set to 246 when reading it, but the print is incorrect.

We are probably missing a flag somewhere

HEAD=@2e9ae51d1e

[toddr]

This can be fixed in bc_parse_perl but to date we have no use case where we want a re-started binary to have an altered STDOUT from the get go.