python
diff --git a/‎Lib/difflib.py‎
Lines changed: 12 additions & 8 deletions b/‎Lib/difflib.py‎
Lines changed: 12 additions & 8 deletions
diff --git a/‎Lib/test/test_difflib.py‎
Lines changed: 8 additions & 0 deletions b/‎Lib/test/test_difflib.py‎
Lines changed: 8 additions & 0 deletions
diff --git a/‎Misc/NEWS.d/next/Library/2018-04-04-23-41-30.bpo-33224.pyR0jB.rst‎
Lines changed: 2 additions & 0 deletions b/‎Misc/NEWS.d/next/Library/2018-04-04-23-41-30.bpo-33224.pyR0jB.rst‎
Lines changed: 2 additions & 0 deletions
@@ -1634,14 +1634,18 @@ def _line_pair_iterator():
                 lines_to_write -= 1
             # Now yield the context lines after the change
             lines_to_write = context-1
-            while(lines_to_write):
-                from_line, to_line, found_diff = next(line_pair_iterator)
-                # If another change within the context, extend the context
-                if found_diff:
-                    lines_to_write = context-1
-                else:
-                    lines_to_write -= 1
-                yield from_line, to_line, found_diff
+            try:
+                while(lines_to_write):
+                    from_line, to_line, found_diff = next(line_pair_iterator)
+                    # If another change within the context, extend the context
+                    if found_diff:
+                        lines_to_write = context-1
+                    else:
+                        lines_to_write -= 1
+                    yield from_line, to_line, found_diff
+            except StopIteration:
+                # Catch exception from next() and return normally
+                return
 
 
 _file_template = """
 
@@ -93,6 +93,14 @@ def test_added_tab_hint(self):
         self.assertEqual("+ \t\tI am a bug", diff[2])
         self.assertEqual("? +\n", diff[3])
 
+    def test_mdiff_catch_stop_iteration(self):
+        # Issue #33224
+        self.assertEqual(
+            list(difflib._mdiff(["2"], ["3"], 1)),
+            [((1, '\x00-2\x01'), (1, '\x00+3\x01'), True)],
+        )
+
+
 patch914575_from1 = """
    1. Beautiful is beTTer than ugly.
    2. Explicit is better than implicit.
 
@@ -0,0 +1,2 @@
+Update difflib.mdiff() for PEP 479.  Convert an uncaught StopIteration in a
+generator into a return-statement.
Original file line number	Diff line number	Diff line change
@@ -0,0 +1,2 @@
	1	+ Update difflib.mdiff() for PEP 479. Convert an uncaught StopIteration in a
	2	+ generator into a return-statement.