getaddrlist(): Make sure this consumes all the data, and if there is

no address there (perhaps because of invalid characters, it appends
('', '') to the result set.

Closes mimelib SF bug # 697641.

Lib/email/_parseaddr.py

@@ -196,12 +196,12 @@ class AddrlistClass:
         Returns a list containing all of the addresses.
         """
         result = []
-        while True:
+        while self.pos < len(self.field):
             ad = self.getaddress()
             if ad:
                 result += ad
             else:
-                break
+                result.append(('', ''))
         return result
 
     def getaddress(self):