Fix #6742: end-before option of literalinclude skips first line

tests/test_directive_code.py

@@ -206,6 +206,14 @@ def test_LiteralIncludeReader_missing_start_and_end(literal_inc_path):
         content, lines = reader.read()
 
 
+def test_LiteralIncludeReader_end_before(literal_inc_path):
+    options = {'end-before': 'nclud'}  # *nclud* matches first and third lines.
+    reader = LiteralIncludeReader(literal_inc_path, options, DUMMY_CONFIG)
+    content, lines = reader.read()
+    assert content == ("# Literally included file using Python highlighting\n"
+                       "\n")
+
+
 @pytest.mark.xfail(os.name != 'posix', reason="Not working on windows")
 def test_LiteralIncludeReader_prepend(literal_inc_path):
     options = {'lines': '1', 'prepend': 'Hello', 'append': 'Sphinx'}