Fix Symlinks not being copies across stages

pkg/commands/copy.go

@@ -85,7 +85,7 @@ func (c *CopyCommand) ExecuteCommand(config *v1.Config, buildArgs *dockerfile.Bu
 				return err
 			}
 			c.snapshotFiles = append(c.snapshotFiles, copiedFiles...)
-		} else if fi.Mode()&os.ModeSymlink != 0 {
+		} else if util.IsSymlink(fi) {
 			// If file is a symlink, we want to create the same relative symlink
 			exclude, err := util.CopySymlink(fullPath, destPath, c.buildcontext)
 			if err != nil {