Fix RecursionError when closing nbAgg figures.

QuLogic · QuLogic · commit c89db64c1713 · 2020-04-04T04:17:39.000-04:00
Previously, if a figure number was not in the list of managed figures,
the destroy would be skipped, but now that only happens if a figure
number is passed. If a figure manager is passed, then the destroy
happens regardless. In nbAgg, this loops around closing/close_event and
eventually calls destroy again, leading to a RecursionError.
diff --git a/lib/matplotlib/_pylab_helpers.py b/lib/matplotlib/_pylab_helpers.py
@@ -57,6 +57,8 @@ def destroy(cls, num):
             manager = num
             if cls.figs.get(manager.num) is manager:
                 cls.figs.pop(manager.num)
+            else:
+                return
         else:
             try:
                 manager = cls.figs.pop(num)
