upload file without overwriting failed

[thinkycx]

When uploading the files , using the request.set_insert_only function and it will still overwriting the files .
That means the function doesn't work.
Could you check it out?

request.set_insert_only(0)
request.set_insert_only(1)

[tenfyzhong]

@thinkycx @liuchang0812
Upload the same file, it will update the upload time even if set_insert_only(1). But if upload a different file with a name has existed in cos, it will failed.