Allow ICNS to change size as ICO does

Tests/test_file_icns.py

@@ -61,11 +61,10 @@ class TestFileIcns(PillowTestCase):
         for w, h, r in im.info['sizes']:
             wr = w * r
             hr = h * r
-            im2 = Image.open(TEST_FILE)
-            im2.size = (w, h, r)
-            im2.load()
-            self.assertEqual(im2.mode, 'RGBA')
-            self.assertEqual(im2.size, (wr, hr))
+            im.size = (w, h, r)
+            im.load()
+            self.assertEqual(im.mode, 'RGBA')
+            self.assertEqual(im.size, (wr, hr))
 
         # Check that we cannot load an incorrect size
         with self.assertRaises(ValueError):

src/PIL/IcnsImagePlugin.py

@@ -251,8 +251,6 @@ class IcnsImageFile(ImageFile.ImageFile):
             self.best_size[0] * self.best_size[2],
             self.best_size[1] * self.best_size[2],
         )
-        # Just use this to see if it's loaded or not yet.
-        self.tile = ("",)
 
     @property
     def size(self):
@@ -286,7 +284,8 @@ class IcnsImageFile(ImageFile.ImageFile):
             )
 
         Image.Image.load(self)
-        if not self.tile:
+        if self.im and self.im.size == self.size:
+            # Already loaded
             return
         self.load_prepare()
         # This is likely NOT the best way to do it, but whatever.
@@ -298,11 +297,6 @@ class IcnsImageFile(ImageFile.ImageFile):
         self.im = im.im
         self.mode = im.mode
         self.size = im.size
-        if self._exclusive_fp:
-            self.fp.close()
-        self.fp = None
-        self.icns = None
-        self.tile = ()
         self.load_end()