When IFD is missing, connect get_ifd() dictionary to Exif

Author: radarhere

Tests/test_image.py

@@ -769,6 +769,14 @@ def test_empty_exif(self) -> None:
         exif.load(b"Exif\x00\x00")
         assert not dict(exif)
 
+    def test_empty_get_ifd(self) -> None:
+        exif = Image.Exif()
+        ifd = exif.get_ifd(0x8769)
+        assert ifd == {}
+
+        ifd[36864] = b"0220"
+        assert exif.get_ifd(0x8769) == {36864: b"0220"}
+
     @mark_if_feature_version(
         pytest.mark.valgrind_known_error, "libjpeg_turbo", "2.0", reason="Known Failing"
     )

src/PIL/Image.py

@@ -4073,7 +4073,7 @@ def get_ifd(self, tag):
                 else:
                     # Interop
                     self._ifds[tag] = self._get_ifd_dict(tag_data, tag)
-        ifd = self._ifds.get(tag, {})
+        ifd = self._ifds.setdefault(tag, {})
         if tag == ExifTags.IFD.Exif and self._hidden_data:
             ifd = {
                 k: v