FIX

jklymak · jklymak · commit cb2c2e92ea20 · 2020-08-19T15:02:41.000-07:00
diff --git a/lib/matplotlib/_layoutgrid.py b/lib/matplotlib/_layoutgrid.py
@@ -502,23 +502,6 @@ def seq_id():
     return '%06d' % next(_layoutboxobjnum)
 
 
-def nonetree(lb):
-    if lb.parent is None:
-        nonechildren(lb)
-        del(lb)
-    else:
-        nonetree(lb.parent)
-
-
-def nonechildren(lb):
-    if lb is None:
-        return
-    for child in lb.children.flat:
-        nonechildren(child)
-        del(child)
-    return
-
-
 def print_children(lb):
     """Print the children of the layoutbox."""
     for child in lb.children:
diff --git a/lib/matplotlib/figure.py b/lib/matplotlib/figure.py
@@ -1805,7 +1805,6 @@ def clf(self, keep_observers=False):
             self._axobservers = cbook.CallbackRegistry()
         self._suptitle = None
         if self.get_constrained_layout():
-            self._layoutgrid = layoutgrid.nonetree(self._layoutgrid)
             self.init_layoutgrid()
         self.stale = True
 
@@ -2573,6 +2572,7 @@ def get_tightbbox(self, renderer, bbox_extra_artists=None):
 
     def init_layoutgrid(self):
         """Initialize the layoutgrid for use in constrained_layout."""
+        del(self._layoutgrid)
         self._layoutgrid = layoutgrid.LayoutGrid(
             parent=None, name='figlb')
 
diff --git a/lib/matplotlib/tests/test_constrainedlayout.py b/lib/matplotlib/tests/test_constrainedlayout.py
@@ -389,10 +389,11 @@ def test_constrained_layout23():
     """
 
     for i in range(2):
-        fig, ax = plt.subplots(num="123", constrained_layout=True, clear=True)
+        fig = plt.figure(constrained_layout=True, clear=True, num="123")
+        gs = fig.add_gridspec(1, 2)
+        sub = gs[0].subgridspec(2, 2)
         fig.suptitle("Suptitle{}".format(i))
 
-
 @image_comparison(['test_colorbar_location.png'],
                   remove_text=True, style='mpl20')
 def test_colorbar_location():
