email with multipart/related content does not round-trip parsebytes/as_bytes #136686
Description
Bug report
Bug description:
import email
import email.parser
import email.policy
with open('sample_email.eml', 'rb') as f:
raw_email = f.read()
policy = email.policy.default.clone(cte_type='8bit', utf8=True, refold_source='none')
parser = email.parser.BytesParser(policy=policy)
decoded_email = parser.parsebytes(raw_email)
print("Defects: %s" % decoded_email.defects)
reencoded_email = decoded_email.as_bytes(policy=policy)
print("Two messages matches: %s" % (raw_email == reencoded_email))sample_email.txt (save it as sample_email.eml)
When ran on different python versions (including 3.13), it raises UnicodeEncodeError:
Defects: []
Traceback (most recent call last):
File "/var/tmp/etienne/sample_email.py", line 13, in <module>
reencoded_email = decoded_email.as_bytes(policy=policy)
File "/usr/lib/python3.13/email/message.py", line 208, in as_bytes
g.flatten(self, unixfrom=unixfrom)
~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/lib/python3.13/email/generator.py", line 117, in flatten
self._write(msg)
~~~~~~~~~~~^^^^^
File "/usr/lib/python3.13/email/generator.py", line 182, in _write
self._dispatch(msg)
~~~~~~~~~~~~~~^^^^^
File "/usr/lib/python3.13/email/generator.py", line 219, in _dispatch
meth(msg)
~~~~^^^^^
File "/usr/lib/python3.13/email/generator.py", line 286, in _handle_multipart
g.flatten(part, unixfrom=False, linesep=self._NL)
~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/lib/python3.13/email/generator.py", line 117, in flatten
self._write(msg)
~~~~~~~~~~~^^^^^
File "/usr/lib/python3.13/email/generator.py", line 182, in _write
self._dispatch(msg)
~~~~~~~~~~~~~~^^^^^
File "/usr/lib/python3.13/email/generator.py", line 219, in _dispatch
meth(msg)
~~~~^^^^^
File "/usr/lib/python3.13/email/generator.py", line 278, in _handle_multipart
self.write(subparts)
~~~~~~~~~~^^^^^^^^^^
File "/usr/lib/python3.13/email/generator.py", line 420, in write
self._fp.write(s.encode('ascii', 'surrogateescape'))
~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^
UnicodeEncodeError: 'ascii' codec can't encode characters in position 330-333: ordinal not in range(128)
CPython versions tested on:
3.13
Operating systems tested on:
Linux