ssoma-mda: Fix RFC-2047 decoding for partially-encoded strings

Avoid:

  TypeError: sequence item 0: expected str instance, bytes found

When an RFC-2047-encoded string contains both an unencoded and an
encoded section.  For example:

  >>> import email.header
  >>> email.header.decode_header('Keld =?ISO-8859-1?Q?J=F8rn_Simonsen?=')
  [(b'Keld ', None), (b'J\xf8rn Simonsen', 'iso-8859-1')]

returns the decoded string in bytes but no charset information for the
first chunk.  I'm not sure what the default charset for header values
is, but RFC 2047 sets itself up to deal with non-ASCII header values
[1], so I'm guessing it's ASCII ;).

[1]: http://tools.ietf.org/html/rfc2047#section-1

diff --git a/ssoma-mda b/ssoma-mda
index d3b54063eb40abae52e97cf7bccda842e44ece02..abbe7bc87b316ef24d784e3c358c608cdaf6c49d 100755 (executable)
--- a/ssoma-mda
+++ b/ssoma-mda
@@ -227,9 +227,13 @@ def _decode_header(string):
     'hello'
     >>> _decode_header(string='=?ISO-8859-1?Q?Keld_J=F8rn_Simonsen?=')
     'Keld Jørn Simonsen'
+    >>> _decode_header(string='Keld =?ISO-8859-1?Q?J=F8rn_Simonsen?=')
+    'Keld Jørn Simonsen'
     """
     chunks = []
     for decoded, charset in _email_header.decode_header(string):
+        if isinstance(decoded, bytes) and not charset:
+            charset = 'ASCII'
         if charset:
             decoded = str(decoded, charset)
         chunks.append(decoded)