bpo-40597: Allow email.contextmanager set_content() to set a null string. (GH-20542)
(cherry picked from commit 4fa61a7732923f92de0f7830c12da48c4cec937f)
Co-authored-by: Mark Sapiro <mark@msapiro.net>
diff --git a/Lib/email/contentmanager.py b/Lib/email/contentmanager.py
index 2b4b875..b91fb0e 100644
--- a/Lib/email/contentmanager.py
+++ b/Lib/email/contentmanager.py
@@ -146,7 +146,7 @@
def normal_body(lines): return b'\n'.join(lines) + b'\n'
if cte==None:
# Use heuristics to decide on the "best" encoding.
- if max(len(x) for x in lines) <= policy.max_line_length:
+ if max((len(x) for x in lines), default=0) <= policy.max_line_length:
try:
return '7bit', normal_body(lines).decode('ascii')
except UnicodeDecodeError: