That is exactly what happened. From XEP-0047, Appendix H: Version History:
Version 2.0 (2012-06-22)
Per a vote of the XMPP Council, advanced to Final; in addition, specified that the 'block-size' attribute defines the size of the data chunk before instead of after base64-encoding, to accord with existing implementations.
Logged as 
SMACK-524