mongodb error point of problem in Test-Simple

gistfile1.pl

#https://github.com/Test-More/test-more/blob/stream/master/lib/Test/Stream/Context.pm#L263
# expanded:

# This still demonstrates problem:
sub snapshot {
    my ($self, $type, $copy, $new);
    $self = shift;
    $type = blessed($self);
    $copy = {%$self};
    $new = bless $copy, $type;
    return $new;
}


# This fixes it:
sub snapshot {
    my ($self, $type, $copy, $new);
    $self = shift;
    $type = blessed($self);
    { local $_; $copy = {%$self}; }
    $new = bless $copy, $type;
    return $new;
}