fix: handle missing 'import' keyword in break_up_import

autoflake.py

@@ -533,12 +533,17 @@ def break_up_import(line: str) -> str:
     if not newline:
         return line
 
-    indentation, imports = re.split(
+    parts = re.split(
         pattern=r"\bimport\b",
         string=line,
         maxsplit=1,
     )
 
+    if len(parts) != 2:
+        # No 'import' keyword found (e.g., a continuation line with \r line endings)
+        return line
+
+    indentation, imports = parts
     indentation += "import "
     assert newline
 

test_autoflake.py

@@ -3619,3 +3619,23 @@ def write(*_: Any) -> None:
 
 if __name__ == "__main__":
     unittest.main()
+
+
+class TestCarriageReturnInImport(unittest.TestCase):
+    """Tests for fix of crash with carriage return in multiline import (issue #326)."""
+
+    def test_carriage_return_in_multiline_parenthesized_import(self):
+        """Should not crash when a line within parenthesized import starts with \r."""
+        source = (
+            "from t import (\n"
+            "\r  a,\n"
+            "    b,\n"
+            ")\n"
+            "from t import (\n"
+            "    a,\n"
+            "    b,\n"
+            ")\n"
+        )
+        # Should not raise ValueError
+        result = autoflake.fix_code(source, remove_all_unused_imports=True)
+        self.assertIsNotNone(result)