message: error out if the reading of the bloom structure failed
diff: @@ -250,7 +250,7 @@ pub fn index_get_header(mut file: &fs::File) -> io::Result<Lookup> {
  }
  let mut bloom : Vec<u8> = repeat(0).take(bloom_size as usize).collect();
  - file.read_exact(&mut bloom[..]);
  + file.read_exact(&mut bloom[..])?;
  Ok(Lookup { fanout: Fanout(fanout), bloom: Bloom(bloom) })
  }
  