diff --git a/lib/matplotlib/backend_bases.py b/lib/matplotlib/backend_bases.py
@@ -45,6 +45,7 @@
 
 import numpy as np
 
+import matplotlib as mpl
 from matplotlib import (
     backend_tools as tools, cbook, colors, textpath, tight_bbox, transforms,
     widgets, get_backend, is_interactive, rcParams)

diff --git a/lib/matplotlib/patches.py b/lib/matplotlib/patches.py
@@ -1667,7 +1667,7 @@ def segment_circle_intersect(x0, y0, x1, y1):
         # circle in the same way that it is relative to the desired ellipse.
         box_path = Path.unit_rectangle()
         box_path_transform = (transforms.BboxTransformTo(self.axes.bbox)
-                              - self.get_transform())
+                              + self.get_transform().inverted())
         box_path = box_path.transformed(box_path_transform)
 
         thetas = set()

diff --git a/lib/matplotlib/tests/test_compare_images.py b/lib/matplotlib/tests/test_compare_images.py
@@ -1,4 +1,3 @@
-import os
 from pathlib import Path
 import shutil
 

diff --git a/lib/matplotlib/tests/test_image.py b/lib/matplotlib/tests/test_image.py
@@ -13,8 +13,7 @@
 from numpy.testing import assert_array_equal
 
 from matplotlib import (
-    colors, image as mimage, patches, pyplot as plt, style,
-    rc_context, rcParams)
+    colors, image as mimage, patches, pyplot as plt, style, rcParams)
 from matplotlib.cbook import MatplotlibDeprecationWarning
 from matplotlib.image import (AxesImage, BboxImage, FigureImage,
                               NonUniformImage, PcolorImage)