Sun Jan 8 22:12:48 GMT 2012 Brian Warner <warner@lothar.com>

Sun Jan  8 22:12:48 GMT 2012  Brian Warner <warner@lothar.com>
  * mutable/retrieve.py: clean up control flow to avoid dropping errors

  * replace DeferredList with gatherResults, simplify result handling
  * use BadShareError to signal recoverable problems in either fetch or
    validate, catch after _validate_block
  * _validate_block is thus not responsible for noticing fetch problems
  * rename _validation_or_decoding_failed() to _handle_bad_share()
  * _get_needed_hashes() returns two Deferreds, instead of a hard-to-unpack
    DeferredList