fix verification in ethcore-sync collect_blocks (#9135)

Author: debris

ethcore/sync/src/block_sync.rs

@@ -477,18 +477,19 @@ impl BlockDownloader {
 		for block_and_receipts in blocks {
 			let block = block_and_receipts.block;
 			let receipts = block_and_receipts.receipts;
-			let (h, number, parent) = {
-				let header = view!(BlockView, &block).header_view();
-				(header.hash(), header.number(), header.parent_hash())
-			};
 
 			// Perform basic block verification
 			if !Block::is_good(&block) {
-				debug!(target: "sync", "Bad block rlp {:?} : {:?}", h, block);
+				debug!(target: "sync", "Bad block rlp: {:?}", block);
 				bad = true;
 				break;
 			}
 
+			let (h, number, parent) = {
+				let header = view!(BlockView, &block).header_view();
+				(header.hash(), header.number(), header.parent_hash())
+			};
+
 			if self.target_hash.as_ref().map_or(false, |t| t == &h) {
 				self.state = State::Complete;
 				trace!(target: "sync", "Sync target reached");