add f.Close() after dockerignore.ReadAll(f) before return err

Signed-off-by: lixiaobing10051267 <li.xiaobing1@zte.com.cn>
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

builder/remotecontext/detect.go

@@ -131,6 +131,7 @@ func removeDockerfile(c modifiableContext, filesToRemove ...string) error {
 	}
 	excludes, err := dockerignore.ReadAll(f)
 	if err != nil {
+		f.Close()
 		return err
 	}
 	f.Close()