Re-enable frame eval: SIGABRT in generator

[Elizaveta239]

Hi! After the latest changes execution of the following code leads to debugger crash with Python 3.6:

def generator2():
    for i in range(4):
        yield i

def generator():
    a = 42  # breakpoint
    yield from generator2()
    return a

sum = 0
for i in generator():
    sum += i

print("The end")

To reproduce: stop at breakpoint, then press resume. It leads to: Fatal Python error: GC object already tracked Process finished with exit code 134 (interrupted by signal 6: SIGABRT)

[fabioz]

I was able to reproduce this. Will check as it seems pretty critical.