Don't add corrupt chunks to verified_chunks

When -persist is specified, the chunk downloader may return the chunk even if
the chunk is corrupt.  We use the chunk.isBroken flag to detect this situation.

src/duplicacy_snapshotmanager.go

@@ -1083,6 +1083,8 @@ func (manager *SnapshotManager) CheckSnapshots(snapshotID string, revisionsToChe
 				if chunk == nil {
 					continue
 				}
+
+				if !chunk.isBroken {
 					chunkID := manager.config.GetChunkIDFromHash(chunkHashes[chunkIndex])
 					verifiedChunksLock.Lock()
 					verifiedChunks[chunkID] = startTime.Unix()
@@ -1097,6 +1099,7 @@ func (manager *SnapshotManager) CheckSnapshots(snapshotID string, revisionsToChe
 					percentage := float64(downloadedChunks) / float64(totalChunks) * 100.0
 					LOG_INFO("VERIFY_PROGRESS", "Verified chunk %s (%d/%d), %sB/s %s %.1f%%",
 							chunkID, downloadedChunks, totalChunks, PrettySize(speed), PrettyTime(remainingTime), percentage)
+				}
 
 				manager.config.PutChunk(chunk)
 			}