Message 369166 - Python tracker

One minor nit:  We're getting a nuisance compiler warning:

test_peg_generator passed (2 min 40 sec)
/var/folders/1b/3499qp8s7xv5w0fvjcgl45100000gn/T/tmp90rifd5z/parse.c:97:19: warning: code will never be executed [-Wunreachable-code]
        p->mark = _mark;
                  ^~~~~
1 warning generated.