Fix unified diff parse error

tests/casefiles/abc

@@ -0,0 +1 @@
+The Nameless is the origin of Heaven and Earth;

tests/casefiles/diff-unified2.diff

@@ -0,0 +1,5 @@
+--- abc	2013-01-05 16:56:19.000000000 -0600
++++ efg	2013-01-05 16:56:35.000000000 -0600
+@@ -1 +1,2 @@
+ The Nameless is the origin of Heaven and Earth;
++The named is the mother of all things.

tests/casefiles/efg

@@ -0,0 +1,2 @@
+The Nameless is the origin of Heaven and Earth;
+The named is the mother of all things.

tests/test_apply.py

@@ -28,6 +28,12 @@ def setUp(self):
         with open("tests/casefiles/tzu") as f:
             self.tzu = f.read().splitlines()
 
+        with open("tests/casefiles/abc") as f:
+            self.abc = f.read().splitlines()
+
+        with open("tests/casefiles/efg") as f:
+            self.efg = f.read().splitlines()
+
     def test_truth(self):
         self.assertEqual(type(self.lao), list)
         self.assertEqual(type(self.tzu), list)
@@ -55,6 +61,13 @@ def test_diff_unified(self):
         self.assertEqual(_apply(self.lao, diff_text), self.tzu)
         self.assertEqual(_apply_r(self.tzu, diff_text), self.lao)
 
+    def test_diff_unified2(self):
+        with open("tests/casefiles/diff-unified2.diff") as f:
+            diff_text = f.read()
+
+        self.assertEqual(_apply(self.abc, diff_text), self.efg)
+        self.assertEqual(_apply_r(self.efg, diff_text), self.abc)
+
     def test_diff_unified_bad(self):
         with open("tests/casefiles/diff-unified-bad.diff") as f:
             diff_text = f.read()
@@ -129,6 +142,22 @@ def test_diff_unified_patchutil(self):
         with pytest.raises(exceptions.ApplyException):
             _apply([""] + self.lao, diff_text, use_patch=True)
 
+    def test_diff_unified2_patchutil(self):
+        with open("tests/casefiles/diff-unified2.diff") as f:
+            diff_text = f.read()
+
+        if not which("patch"):
+            raise SkipTest()
+
+        self.assertEqual(_apply(self.abc, diff_text, use_patch=True),
+                         (self.efg, None))
+        self.assertEqual(_apply(self.abc, diff_text, use_patch=True),
+                         (_apply(self.abc, diff_text), None))
+        self.assertEqual(_apply_r(self.efg, diff_text, use_patch=True),
+                         (self.abc, None))
+        self.assertEqual(_apply_r(self.efg, diff_text, use_patch=True),
+                         (_apply_r(self.efg, diff_text), None))
+
     def test_diff_rcs(self):
         with open("tests/casefiles/diff-rcs.diff") as f:
             diff_text = f.read()

tests/test_patch.py

@@ -857,6 +857,34 @@ def test_unified_diff(self):
         results_main = next(wtp.patch.parse_patch(text))
         self.assert_diffs_equal(results_main, expected_main)
 
+    def test_unified2_diff(self):
+        with open(datapath("diff-unified2.diff")) as f:
+            text = f.read()
+
+        # off with your head!
+        text_diff = "\n".join(text.splitlines()[2:]) + "\n"
+
+        expected = [
+            (None, 2, "The named is the mother of all things."),
+        ]
+
+        results = list(wtp.patch.parse_unified_diff(text_diff))
+        self.assert_diffs_equal(results, expected)
+
+        expected_main = diffobj(
+            header=headerobj(
+                index_path=None,
+                old_path="abc",
+                old_version="2013-01-05 16:56:19.000000000 -0600",
+                new_path="efg",
+                new_version="2013-01-05 16:56:35.000000000 -0600",
+            ),
+            changes=expected,
+            text=text,
+        )
+        results_main = next(wtp.patch.parse_patch(text))
+        self.assert_diffs_equal(results_main, expected_main)
+
     def test_diff_unified_with_does_not_include_extra_lines(self):
         with open("tests/casefiles/diff-unified-blah.diff") as f:
             text = f.read()

whatthepatch/patch.py

@@ -622,8 +622,9 @@ def parse_unified_diff(text):
                 elif kind == "+" and (i != new_len or i == 0):
                     changes.append(Change(None, new + i, line, hunk_n))
                     i += 1
-                elif kind == " " and r != old_len and i != new_len:
-                    changes.append(Change(old + r, new + i, line, hunk_n))
+                elif kind == " ":
+                    if r != old_len and i != new_len:
+                        changes.append(Change(old + r, new + i, line, hunk_n))
                     r += 1
                     i += 1