Don't mark a patch transform as set if the parent transform is not set.

anntzer · anntzer · commit 89846f1a1cf7 · 2018-06-24T00:51:37.000+02:00
When updating a patch from another artist, if the other artist's
transform is marked as "uninitialized" (`_transformSet == False`), then
don't mark the updatee's transform as set either.

Typically, this occurs if the updator has not been added to an Axes yet;
its transform will be set when that adding occurs.  In that case, the
updatee's transform also needs to be set when actually being added to an
Axes.
diff --git a/lib/matplotlib/patches.py b/lib/matplotlib/patches.py
@@ -175,6 +175,9 @@ def update_from(self, other):
         self._us_dashes = other._us_dashes
         self.set_linewidth(other._linewidth)  # also sets dash properties
         self.set_transform(other.get_data_transform())
+        # If the transform of other needs further initialization, then it will
+        # be the case for this artist too.
+        self._transformSet = other.is_transform_set()
 
     def get_extents(self):
         """
