In fixed-size chunking, create a new chunk after returning the old one

integration_tests/fixed_test.sh

@@ -0,0 +1,18 @@
+#!/bin/bash
+
+# Sanity test for the fixed-size chunking algorithm
+
+. ./test_functions.sh
+
+fixture
+
+pushd ${TEST_REPO}
+${DUPLICACY} init integration-tests $TEST_STORAGE -c 64 -max 64 -min 64 
+
+add_file file3
+add_file file4
+
+
+${DUPLICACY} backup 
+${DUPLICACY} check --files -stats
+popd

src/duplicacy_backupmanager.go

@@ -1132,7 +1132,7 @@ func (manager *BackupManager) RestoreFile(chunkDownloader *ChunkDownloader, chun
                 fileHash = hash
                 return nil, false
             })
-        if fileHash == entry.Hash {
+        if fileHash == entry.Hash && fileHash != "" {
             LOG_TRACE("DOWNLOAD_SKIP", "File %s unchanged (by hash)", entry.Path)
             return false
         }

src/duplicacy_chunkmaker.go

@@ -146,7 +146,6 @@ func (maker *ChunkMaker) ForEachChunk(reader io.Reader, endOfChunk func(chunk *C
         }
 
         for {
-            startNewChunk()
             maker.bufferStart = 0
             for maker.bufferStart < maker.minimumChunkSize && !isEOF {
                 count, err := reader.Read(maker.buffer[maker.bufferStart : maker.minimumChunkSize])
@@ -174,6 +173,7 @@ func (maker *ChunkMaker) ForEachChunk(reader io.Reader, endOfChunk func(chunk *C
                     return
                 } else {
                     endOfChunk(chunk, false)
+                    startNewChunk()
                     fileSize = 0
                     fileHasher = maker.config.NewFileHasher()
                     isEOF = false