Merge pull request #267 from ethcore/garbage-test-fix

Garbage collection test fix

src/blockchain.rs

@@ -785,8 +785,9 @@ mod tests {
 		}
 		assert!(bc.cache_size().blocks > 1024 * 1024);
 
+		for _ in 0..2 {
 			bc.collect_garbage(true);
-
+		}
 		assert!(bc.cache_size().blocks < 1024 * 1024);
 	}