Update comment for getaddresses() and fix broken email test

Author: tdwyer

Lib/email/utils.py

@@ -131,12 +131,18 @@ def _post_parse_validation(parsed_email_header_tuples):
 
 def getaddresses(fieldvalues):
     """Return a list of (REALNAME, EMAIL) or ('','') for each fieldvalue.
-    
+
     When parsing fails for a fieldvalue, a 2-tuple of ('', '') is returned in
     its place.
 
-    If the resulting list is greater than number of items in the fieldvalues
-    list, a list containing a single empty 2-tuple [('', '')] will be returned.
+    If the resulting list of parsed address is greater than number of
+    fieldvalues in the input list a parsing error has occurred, so a list
+    containing a single empty 2-tuple [('', '')] is returned in its place.
+    This is done to avoid invalid output.
+
+    Malformed input: getaddresses(['[email protected] <[email protected]>'])
+    Invalid output: [('', '[email protected]'), ('', '[email protected]')]
+    Safe output: [('', '')]
     """
     fieldvalues = [str(v) for v in fieldvalues]
     fieldvalues = _pre_parse_validation(fieldvalues)

Lib/test/test_email/test_email.py

@@ -3402,7 +3402,7 @@ def test_getaddresses_nasty(self):
            [('', '')])
         eq(utils.getaddresses(
            [r'<[email protected]>, "Giant; \"Big\" Box" <[email protected]>']),
-           [('', '[email protected]'), ('Giant;  Big  Box', '[email protected]')])
+           [('', '[email protected]'), ('Giant; "Big" Box', '[email protected]')])
 
     def test_getaddresses_embedded_comment(self):
         """Test proper handling of a nested comment"""