gh-125651: Fix UUID hex parsing with underscores

Author: sevdog

Lib/test/test_uuid.py

@@ -277,6 +277,8 @@ def test_exceptions(self):
         # Badly formed hex strings.
         badvalue(lambda: self.uuid.UUID(''))
         badvalue(lambda: self.uuid.UUID('abc'))
+        badvalue(lambda: self.uuid.UUID("123_4567812345678123456781234567"))
+        badvalue(lambda: self.uuid.UUID("123_4567812345678123456781_23456"))
         badvalue(lambda: self.uuid.UUID('1234567812345678123456781234567'))
         badvalue(lambda: self.uuid.UUID('123456781234567812345678123456789'))
         badvalue(lambda: self.uuid.UUID('123456781234567812345678z2345678'))

Lib/uuid.py

@@ -214,7 +214,7 @@ def __init__(self, hex=None, bytes=None, bytes_le=None, fields=None,
             pass
         elif hex is not None:
             hex = hex.replace('urn:', '').replace('uuid:', '')
-            hex = hex.strip('{}').replace('-', '')
+            hex = hex.strip("{}").replace("-", "").replace("_", "")
             if len(hex) != 32:
                 raise ValueError('badly formed hexadecimal UUID string')
             int = int_(hex, 16)