Fix test and code.

Author: lajiyuan

Tests/test_file_png.py

@@ -777,6 +777,16 @@ class MyStdOut:
             mystdout = mystdout.buffer
         with Image.open(mystdout) as reloaded:
             assert_image_equal_tofile(reloaded, TEST_PNG_FILE)
+    
+    def test_end_truncated_filed(self):
+        ImageFile.LOAD_TRUNCATED_IMAGES = True
+        try:
+            img =  Image.open("Tests/images/end_trunc_file.png")
+            img.load()
+            assert img is not None
+        finally:
+            ImageFile.LOAD_TRUNCATED_IMAGES = False
+
 
 
 @pytest.mark.skipif(is_win32(), reason="Requires Unix or macOS")
@@ -786,20 +796,18 @@ class TestTruncatedPngPLeaks(PillowLeakTestCase):
     iterations = 100  # Leak is 56k/iteration, this will leak 5.6megs
 
     def test_leak_load(self):
-        files = ['Tests/images/hopper.png', 'Tests/images/end_trunc_file.png']
-        for file in files:
-            with open(file, "rb") as f:
-                DATA = BytesIO(f.read(16 * 1024))
+        with open("Tests/images/hopper.png", "rb") as f:
+            DATA = BytesIO(f.read(16 * 1024))
 
-            ImageFile.LOAD_TRUNCATED_IMAGES = True
+        ImageFile.LOAD_TRUNCATED_IMAGES = True
+        with Image.open(DATA) as im:
+            im.load()
+
+        def core():
             with Image.open(DATA) as im:
                 im.load()
 
-            def core():
-                with Image.open(DATA) as im:
-                    im.load()
-
-            try:
-                self._test_leak(core)
-            finally:
-                ImageFile.LOAD_TRUNCATED_IMAGES = False
+        try:
+            self._test_leak(core)
+        finally:
+            ImageFile.LOAD_TRUNCATED_IMAGES = False

src/PIL/PngImagePlugin.py

@@ -984,9 +984,7 @@ def load_end(self):
                 try:
                     ImageFile._safe_read(self.fp, length)
                 except OSError as e:
-                    if (
-                        str(e) == "Truncated File Read"
-                    ) and ImageFile.LOAD_TRUNCATED_IMAGES:
+                    if ImageFile.LOAD_TRUNCATED_IMAGES:
                         logger.debug("%r %s %s (Truncated File Read)", cid, pos, length)
                         break
                     else: