digest-md5 response contains BASE64 padding character in non-last position
Authentic BASE64 data from gajim SASL DIGEST-MD5 response: "Y2hhcnNldD11dGYtOCx1c2VybmFtZT0iYWxiZXJ0IixyZWFsbT0icsOla2F0LnNlIixub25jZT0iNw==NjQ2NzI1OCIsbmM9MDAwMDAwMDEsY25vbmNlPSI3YWMzYWY3NGQxMzZjMTM0Njk0NjM0NDg2N2IwNzM2ZDY5M2FiOTRhODE4M2U0YWI0IixkaWdlc3QtdXJpPSJ4bXBwL3LDpWthdC5zZSIscmVzcG9ucw==ZT1jZmQxMDI5NjZkOTBhNjY1NTljM2IyMzMxZTVjMTEwYSxxb3A9YXV0aA=="
From http://xmpp.org/internet-drafts/draft-saintandre-rfc3920bis-08.html#security-base64
An implementation MUST NOT break on invalid input and MUST reject any sequence of base64 characters containing the pad ('=') character if that character is included as something other than the last character of the data (e.g., "=AAA" or "BBBB=CCC"); this helps to guard against buffer overflow attacks and other attacks on the implementation.
Python 2.6, if that is relevant.