matplotlib
diff --git a/‎lib/matplotlib/backends/backend_qt5.py
Copy file name to clipboardExpand all lines: lib/matplotlib/backends/backend_qt5.py
+4-2Lines changed: 4 additions & 2 deletions b/‎lib/matplotlib/backends/backend_qt5.py
Copy file name to clipboardExpand all lines: lib/matplotlib/backends/backend_qt5.py
+4-2Lines changed: 4 additions & 2 deletions
@@ -1034,9 +1034,11 @@ def trigger_manager_draw(manager):
     def mainloop():
         old_signal = signal.getsignal(signal.SIGINT)
         # allow SIGINT exceptions to close the plot window.
-        signal.signal(signal.SIGINT, signal.SIG_DFL)
+        if old_signal:
+            signal.signal(signal.SIGINT, signal.SIG_DFL)
         try:
             qApp.exec_()
         finally:
             # reset the SIGINT exception handler
-            signal.signal(signal.SIGINT, old_signal)
+            if old_signal:
+                signal.signal(signal.SIGINT, old_signal)