should check if the dataDir folder exits instead of checking dataTar file (#60)

Signed-off-by: Jie Xu <jie.xu@image-metrics.com>
Co-authored-by: Jie Xu <jie.xu@image-metrics.com>

Author: tsujie

pkg/app/master/command/build/image.go

@@ -430,7 +430,7 @@ func buildOutputImage(
 			hasData = true
 		} else {
 			dataDir := filepath.Join(imageInspector.ArtifactLocation, "files")
-			if fsutil.Exists(dataTar) && fsutil.IsDir(dataDir) {
+			if fsutil.Exists(dataDir) && fsutil.IsDir(dataDir) {
 				layerInfo := imagebuilder.LayerDataInfo{
 					Type:   imagebuilder.DirSource,
 					Source: dataDir,