Code review comment for lp:~vila/bzr/1606203-long-auth

str.encode('base64') is equivalent to base64.encodestring(str), which is a legacy interface (https://docs.python.org/2/library/base64.html#base64.encodestring) that returns "one or more lines of base64-encoded data". In particular, it splits the input string into 57-character chunks and encodes each one using binascii.b2a_base64, which adds a newline after each encoded chunk. Thus, if the input string is longer than 57 characters, str.encode('base64').strip() will end up containing embedded newlines.

base64.encodestring exists to encode strings according to RFC 1521's base64 Content-Transfer-Encoding, which has a 76-character limit for each encoded line. It does not make sense to use this for HTTP headers. For that, the base64 module's modern interface, which encodes according to RFC 3548, is more appropriate; and Vincent's patch switches to that.