ARC block release-only block crash

gistfile1.m

- (AFHTTPRequestOperation *)operationForEmptyResponseRequest:(NSURLRequest*) request onComplete:(void(^)(void)) completeBlock onError:(void (^)(NSError *)) errorBlock {
    void (^nilObjectCompleteBlock)(id);
    if (complete) {
        void (^heapCompleteBlock)(void) = [completeBlock copy];
        // INTERESTING BITS:
        // iOS7: this crashes in weird ways if we don't copy the block we assign to nilObjectComplete here.
        // it is supposed to be safe to pass a block down into another block, but maybe not.
        nilObjectCompleteBlock = [^(id nilObject) {
            heapCompleteBlock();
        } copy];
    } else {
        nilObjectCompleteBlock = NULL;
    }
    AFURLConnectionOperation operation = [AFURLConnectionOperation HTTPRequestOperationWithRequest:request
                                                                                           success:(^(AFHTTPRequestOperation *operation, id responseObject) {
      if (nilObjectCompleteBlock) {
        nilObjectCompleteBlock();
      }
    })
                                                                                           failure:(^(AFHTTPRequestOperation *operation, NSError *error) {
      if (errorBlock) {
        errorBlock(error);
      }
    })];
    return operation;
}