rex.sendmail: fix for duplicate Content-Type in html messages

Author: xi-prometheus

src/rex.sendmail/src/rex/sendmail.py

@@ -88,6 +88,7 @@ def compose(template_path, html_template_path=None, **arguments):
     jinja = get_jinja()
     text = jinja.get_template(template_path).render(**arguments)
     text_message = email.message_from_string(text)
+    msg_headers = list(text_message.items())
     body_text = text_message.get_payload()
     text_message.set_charset('utf-8')
 
@@ -125,8 +126,9 @@ def compose(template_path, html_template_path=None, **arguments):
 
         # Redefine message as alternative with html and tect attachments
         message = email.mime.multipart.MIMEMultipart('alternative')
-        for k, v in text_message.items():
+        for k, v in msg_headers:
             message[k] = v
+            del text_message[k]
         message.attach(text_message)
         message.attach(html_message) # the last attachment is preferred
 

src/rex.sendmail/test/test_sendmail.rst

@@ -131,11 +131,8 @@ src="cid:path" >``::
       From: Alice Anderson <[email protected]>
       To: Bob Brown <[email protected]>
       Subject: Hi there!
-      MIME-Version: 1.0
-      Content-Type: multipart/alternative; boundary="..."
-      Content-Transfer-Encoding: base64
     STRUCTURE:
-      type=multipart/alternative, disposition=None, encoding=base64, id=None
+      type=multipart/alternative, disposition=None, encoding=None, id=None
           type=text/plain, disposition=None, encoding=base64, id=None
           type=multipart/related, disposition=None, encoding=None, id=None
               type=text/html, disposition=None, encoding=7bit, id=None