Do not assign new fp attribute to image when exiting context manager

Tests/test_image.py

@@ -1015,6 +1015,11 @@ def test_fli_overrun2(self):
             except OSError as e:
                 assert str(e) == "buffer overrun when reading image file"
 
+    def test_exit_fp(self):
+        with Image.new("L", (1, 1)) as im:
+            pass
+        assert not hasattr(im, "fp")
+
     def test_close_graceful(self, caplog):
         with Image.open("Tests/images/hopper.jpg") as im:
             copy = im.copy()

src/PIL/Image.py

@@ -528,14 +528,15 @@ def __enter__(self):
         return self
 
     def __exit__(self, *args):
-        if hasattr(self, "fp") and getattr(self, "_exclusive_fp", False):
-            if getattr(self, "_fp", False):
-                if self._fp != self.fp:
-                    self._fp.close()
-                self._fp = DeferredError(ValueError("Operation on closed image"))
-            if self.fp:
-                self.fp.close()
-        self.fp = None
+        if hasattr(self, "fp"):
+            if getattr(self, "_exclusive_fp", False):
+                if getattr(self, "_fp", False):
+                    if self._fp != self.fp:
+                        self._fp.close()
+                    self._fp = DeferredError(ValueError("Operation on closed image"))
+                if self.fp:
+                    self.fp.close()
+            self.fp = None
 
     def close(self):
         """