Fix split lines for Python code

Some characters like Vertical Tab or File Separator were used as line separators.
This is not legal. Line Separators in Python are only Carriage Return \r and Line Feed \n.

test/test_utils.py

@@ -29,6 +29,12 @@ import pytest
 
         ('\r', ['', ''], False),
         ('\r', ['\r', ''], True),
+
+        # Invalid line breaks
+        ('a\vb', ['a\vb'], False),
+        ('a\vb', ['a\vb'], True),
+        ('\x1C', ['\x1C'], False),
+        ('\x1C', ['\x1C'], True),
     ]
 )
 def test_split_lines(string, expected_result, keepends):