Fix the change made for issue 1243654.
Surprisingly, it turns out there was no test that exercised this code path.
diff --git a/Lib/email/generator.py b/Lib/email/generator.py
index 510f68b..9d33f1c 100644
--- a/Lib/email/generator.py
+++ b/Lib/email/generator.py
@@ -226,7 +226,8 @@
# Create a boundary that doesn't appear in any of the
# message texts.
alltext = self._encoded_NL.join(msgtexts)
- msg.set_boundary(self._make_boundary(alltext))
+ boundary = self._make_boundary(alltext)
+ msg.set_boundary(boundary)
# If there's a preamble, write it out, with a trailing CRLF
if msg.preamble is not None:
self.write(msg.preamble + self._NL)