emacs 26.1 python-mode bug report C-c C-c won't work at the second time

[john doe <ifvwm@yandex.com>]

   I use emacs open a python-tkinter-test.py, and press C-c C-c it will
   pop a tk window, then i close this window,

   but when i press the second C-c C-c it shows nothings, *Python* is
   still exist, python is still in process list,

   but *Python* won't run anything what it will receive any more, A it
   seems emacs don't think the last one is over, or the new one

   doesn't have an end character,

   A

   this is the python code:

   from Tkinter import *
   A
   root = Tk()
   topFrame = Frame(root)
   topFrame.pack(side=TOP)
   A
   middleFrame = Frame(root)
   middleFrame.pack(side=RIGHT)
   A
   bottomFrame = Frame(root, bg="green")
   bottomFrame.pack(side=BOTTOM)
   A
   topFrame_Label = Label(topFrame, text="Welcome to Python GUI(Top
   Frame)")
   topFrame_Label.pack()
   A
   middleFrame_Label = Label(middleFrame, text="Welcome to Python
   GUI(Middle Frame)")
   middleFrame_Label.pack()
   A
   bottomFrame_Label = Label(bottomFrame, text="Welcome to Python
   GUI(Bottom Frame)")
   bottomFrame_Label.pack()
   A
   root.minsize(400, 400)
   root.mainloop()
   A
   A
   A