Add test stolen from @jklymak matplotlib#20260; fix flake8 warning.

Author: efiring

lib/matplotlib/legend_handler.py

@@ -31,7 +31,6 @@ def legend_artist(self, legend, orig_handle, fontsize, handlebox)
 from matplotlib.lines import Line2D
 from matplotlib.patches import Rectangle
 import matplotlib.collections as mcoll
-import matplotlib.colors as mcolors
 
 
 def update_from_first_child(tgt, src):

lib/matplotlib/tests/test_legend.py

@@ -765,3 +765,11 @@ def test_plot_multiple_label_incorrect_length_exception():
         label = ['high', 'low', 'medium']
         fig, ax = plt.subplots()
         ax.plot(x, y, label=label)
+
+
+def test_legend_face_edgecolor():
+    # Smoke test for PolyCollection legend handler with 'face' edgecolor.
+    fig, ax = plt.subplots()
+    ax.fill_between([0, 1, 2], [1, 2, 3], [2, 3, 4],
+                    facecolor='r', edgecolor='face', label='Fill')
+    ax.legend()