Revert "Forgive the case when a whiteout file trying to cover nonexis…

…tent path (#358)" (#360)

This reverts commit 026a501.

lib/snapshot/mem_layer.go

@@ -23,7 +23,6 @@ import (
 	"sort"
 	"strings"
 
-	"github.com/uber/makisu/lib/log"
 	"github.com/uber/makisu/lib/pathutils"
 	"github.com/uber/makisu/lib/tario"
 )
@@ -115,9 +114,7 @@ func (f *whiteoutMemFile) updateMemFS(node *memFSNode) error {
 			if i != len(parts)-1 {
 				return fmt.Errorf("missing intermediate dir %s in %s", part, f.del)
 			}
-			// This could happen to files that's cleaned up in the background, like
-			// python package's .dist-info or .pth file.
-			log.Warnf("Trying to whiteout nonexistent path: %s", f.del)
+			return fmt.Errorf("whiteout nonexistent path %s", f.del)
 		}
 	}
 	return nil