Ctrl+C does not exit cleanly

[lukehutch]

Describe the bug From the commandline, I have to press Ctrl+C many times to quit gdbgui:

$ gdbgui
Opening gdbgui with default browser at http://127.0.0.1:5000
View gdbgui dashboard at http://127.0.0.1:5000/dashboard
exit gdbgui by pressing CTRL+C
^CTraceback (most recent call last):
  File "src/gevent/libev/corecext.pyx", line 561, in gevent.libev.corecext.loop.handle_error
  File "gevent/hub.py", line 513, in handle_error
  File "gevent/hub.py", line 480, in _normalize_exception
KeyboardInterrupt
Exception ignored in: 'gevent.libev.corecext.gevent_handle_error'
Traceback (most recent call last):
  File "src/gevent/libev/corecext.pyx", line 561, in gevent.libev.corecext.loop.handle_error
  File "gevent/hub.py", line 513, in handle_error
  File "gevent/hub.py", line 480, in _normalize_exception
KeyboardInterrupt: 

^CTraceback (most recent call last):
  File "src/gevent/libev/corecext.pyx", line 561, in gevent.libev.corecext.loop.handle_error
  File "gevent/hub.py", line 513, in handle_error
KeyboardInterrupt
Exception ignored in: 'gevent.libev.corecext.gevent_handle_error'
Traceback (most recent call last):
  File "src/gevent/libev/corecext.pyx", line 561, in gevent.libev.corecext.loop.handle_error
  File "gevent/hub.py", line 513, in handle_error
KeyboardInterrupt: 
^CTraceback (most recent call last):
  File "src/gevent/libev/corecext.pyx", line 561, in gevent.libev.corecext.loop.handle_error
  File "gevent/hub.py", line 487, in handle_error
KeyboardInterrupt
Exception ignored in: 'gevent.libev.corecext.gevent_handle_error'
Traceback (most recent call last):
  File "src/gevent/libev/corecext.pyx", line 561, in gevent.libev.corecext.loop.handle_error
  File "gevent/hub.py", line 487, in handle_error
KeyboardInterrupt: 
^CTraceback (most recent call last):
  File "src/gevent/libev/corecext.pyx", line 561, in gevent.libev.corecext.loop.handle_error
  File "gevent/hub.py", line 513, in handle_error
KeyboardInterrupt
Exception ignored in: 'gevent.libev.corecext.gevent_handle_error'
Traceback (most recent call last):
  File "src/gevent/libev/corecext.pyx", line 561, in gevent.libev.corecext.loop.handle_error
  File "gevent/hub.py", line 513, in handle_error
KeyboardInterrupt: 
^CTraceback (most recent call last):
  File "src/gevent/libev/corecext.pyx", line 561, in gevent.libev.corecext.loop.handle_error
  File "gevent/hub.py", line 513, in handle_error
  File "gevent/hub.py", line 474, in _normalize_exception
KeyboardInterrupt
Exception ignored in: 'gevent.libev.corecext.gevent_handle_error'
Traceback (most recent call last):
  File "src/gevent/libev/corecext.pyx", line 561, in gevent.libev.corecext.loop.handle_error
  File "gevent/hub.py", line 513, in handle_error
  File "gevent/hub.py", line 474, in _normalize_exception
KeyboardInterrupt: 
^CTraceback (most recent call last):
  File "src/gevent/libev/corecext.pyx", line 561, in gevent.libev.corecext.loop.handle_error
  File "gevent/hub.py", line 487, in handle_error
KeyboardInterrupt
Exception ignored in: 'gevent.libev.corecext.gevent_handle_error'
Traceback (most recent call last):
  File "src/gevent/libev/corecext.pyx", line 561, in gevent.libev.corecext.loop.handle_error
  File "gevent/hub.py", line 487, in handle_error
KeyboardInterrupt: 
^CKeyboardInterrupt
2021-05-18T03:22:26Z

Please complete the following information:

• OS: Fedora Linux 33
• gdbgui version (gdbgui -v): gdbgui_0.14.0.2
• gdb version (gdb -v): N/A
• browser [e.g. chrome, safari]: Chrome
• python packages (pip freeze): N/A