(feature) pydela gets stuck in z3 assertion error

[rainoftime]

When Z3 throws an assertion error,
the process will get stuck.
As a result, some delta debuggers like ddSMT and pydelta can get stuck in the first run.

An example
z3stuck.txt

---

Previously, I modified ddSMT to support this.

    proc = subprocess.Popen(g_args.cmd, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
    timer = Timer(g_time_limit, terminate, args=[proc])
    timer.start()
    try:
      for line in iter(proc.stdout.readline, ''):
         ...

    proc.stdout.close()
    procstat = proc.wait()
    timer.cancel()