shift generates bad code when used to grab sub args

[snoopyjc]

Given this code:

sub issue_8
{
    $arg1 = shift;
    my $arg2 = shift;
}

The code generated for "$arg1 = shift;" is "arg1=.pop(0)", which is a syntax error in python. Same for $arg2.

[snoopyjc]

Fixed in https://github.com/snoopyjc/pythonizer