fix: prevent remove unicode whitespace when parsing atx heading

lepture · lepture · commit 9e72063501c6 · 2025-08-29T14:34:42.000+09:00
ref #414
diff --git a/src/mistune/block_parser.py b/src/mistune/block_parser.py
@@ -1,5 +1,6 @@
 import re
 from typing import Optional, List, Tuple, Match, Pattern
+import string
 from .util import (
     unikey,
     escape_url,
@@ -185,7 +186,7 @@ def parse_atx_heading(self, m: Match[str], state: BlockState) -> int:
         """Parse token for ATX heading. An ATX heading is started with 1 to 6
         symbol of ``#``."""
         level = len(m.group("atx_1"))
-        text = m.group("atx_2").strip()
+        text = m.group("atx_2").strip(string.whitespace)
         # remove last #
         if text:
             text = _ATX_HEADING_TRIM.sub("", text)
