mail: document behavior of Python 3
test-notify.t (and possibly other tests) are failing on Python 3
because email.message.Message is now aware of encodings and
attempts to roundtrip values with the specified message encoding.
Python 2 doesn't perform this roundtripping. We have tests with
non-ascii data being serialized to a message that claims to use
ascii encoding.
I /think/ Mercurial's behavior may be buggy here. But I'm not
sure.
I'm documenting the behavior so the next person who looks into
this doesn't start from scratch like I did.
Differential Revision: https://phab.mercurial-scm.org/D5714
--- a/mercurial/mail.py Sat Jan 26 10:22:09 2019 -0800
+++ b/mercurial/mail.py Sat Jan 26 10:40:37 2019 -0800
@@ -243,6 +243,13 @@
cs.body_encoding = email.charset.QP
break
+ # On Python 2, this simply assigns a value. Python 3 inspects
+ # body and does different things depending on whether it has
+ # encode() or decode() attributes. We can get the old behavior
+ # if we pass a str and charset is None and we call set_charset().
+ # But we may get into trouble later due to Python attempting to
+ # encode/decode using the registered charset (or attempting to
+ # use ascii in the absence of a charset).
msg.set_payload(body, cs)
return msg