flake8: rename loop variable in 'for sendto in sendto:'

Flake8 reported 'B020 Found for loop that reassigns the iterable it is
iterating with each iterable value.'

Renamed loop variable to to_addr. There is a similar construct with a
loop over bcc_sendto with a 'bcc' loop variable. So I assume the loop
varaible can be chnaged w/o issue.

Codecov shows all the affected lines are being tested and the tests I
ran with testmon that should cover that code all passed.

We shall see if a full CI run passes.

CHANGES.txt

@@ -25,6 +25,8 @@ Fixed:
 - issue2551283 - fail if version 2.4.9 of markdown2 is used, it broke
   [issue1](issue1) style links. Support markdown2 2.4.8 and earlier
   and 2.4.10 with its new schema filtering method. (John Rouillard)
+- multiple flake8 fixes (John Rouillard)
+- rename loop variable in 'for sendto in sendto:' (John Rouillard)
 
 Features:
 

roundup/roundupdb.py

@@ -577,7 +577,7 @@ def send_message(self, issueid, msgid, note, sendto, from_address=None,
         # can't fiddle the recipients in the message ... worth testing
         # and/or fixing some day
         first = True
-        for sendto in sendto:
+        for to_addr in sendto:
             # create the message
             mailer = Mailer(self.db.config)
 
@@ -721,18 +721,18 @@ def send_message(self, issueid, msgid, note, sendto, from_address=None,
                 message.set_payload(body, message.get_charset())
 
             if crypt:
-                send_msg = self.encrypt_to(message, sendto)
+                send_msg = self.encrypt_to(message, to_addr)
             else:
                 send_msg = message
-            mailer.set_message_attributes(send_msg, sendto, subject, author)
+            mailer.set_message_attributes(send_msg, to_addr, subject, author)
             if crypt:
                 send_msg['Message-Id'] = message['Message-Id']
                 send_msg['Reply-To'] = message['Reply-To']
                 if message.get('In-Reply-To'):
                     send_msg['In-Reply-To'] = message['In-Reply-To']
 
-            if sendto:
-                mailer.smtp_send(sendto, send_msg.as_string())
+            if to_addr:
+                mailer.smtp_send(to_addr, send_msg.as_string())
             if first:
                 if crypt:
                     # send individual bcc mails, otherwise receivers can