It was missing a closing bracket just before the ";" in that line. This works:

sub get_login_env {
  local %ENV;
  my $shell = shift || (getpwuid($<))[8];
  my $env = `echo env | perl -e 'exec {"$shell"} -sh'`;
  if (wantarray) {
    my @pieces = ($env =~ m/^(.*?)=((?:[^\n\\]|\\.|\\\n)*)/gm );
    s/\\(.)/$1/g foreach @pieces;
    return @pieces;
  }
  else {
    return $env;
  }
}
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Cheers, Sören