title: Helm always reports a 403 error when adding minio repo
body: <p>I have run the latest version of minio with Docker and can access it normally by browser.
  Then I installed the MC client and tested Minio with MC, and everything worked fine.
  but when I use helm add the minio repo. I get a 403 error.</p>
  
  <pre><code>[root@k8smaster01 helm-charts]# mc config host list
  gcs    
    URL       : https://storage.googleapis.com
    AccessKey : YOUR-ACCESS-KEY-HERE
    SecretKey : YOUR-SECRET-KEY-HERE
    API       : S3v2
    Lookup    : dns
  
  local  
    URL       : http://localhost:9000
    AccessKey : 
    SecretKey : 
    API       : 
    Lookup    : auto
  
  myminio
    URL       : http://172.16.5.182:9000
    AccessKey : minioadmin
    SecretKey : minioadmin
    API       : s3v4
    Lookup    : auto
  
  play   
    URL       : https://play.min.io
    AccessKey : Q3AM3UQ867SPQQA43P2F
    SecretKey : zuf+tfteSlswRu7BJ86wekitnifILbZam1KYY3TG
    API       : S3v4
    Lookup    : auto
  
  s3     
    URL       : https://s3.amazonaws.com
    AccessKey : YOUR-ACCESS-KEY-HERE
    SecretKey : YOUR-SECRET-KEY-HERE
    API       : S3v4
    Lookup    : dns
  
  [root@k8smaster01 helm-charts]# mc ls myminio
  [2020-06-16 18:10:01 CST]      0B minio-helm-repo/
  [root@k8smaster01 helm-charts]# mc ls myminio/minio-helm-repo/
  \[2020-06-16 18:17:20 CST]     76B index.yaml
  [root@k8smaster01 helm-charts]# helm repo add minio-test-repo http://172.16.5.182:9000/minio-helm-repo
  Error: looks like "http://172.16.5.182:9000/minio-helm-repo" is not a valid chart repository or cannot be reached: failed to fetch http://172.16.5.182:9000/minio-helm-repo/index.yaml : 403 Forbidden
  [root@k8smaster01 helm-charts]#
  [root@k8smaster01 helm-charts]# helm repo add minio-test-repo http://172.16.5.182:9000/minio-helm-repo --username minioadmin --password minioadmin
  Error: looks like "http://172.16.5.182:9000/minio-helm-repo" is not a valid chart repository or cannot be reached: failed to fetch http://172.16.5.182:9000/minio-helm-repo/index.yaml : 400 Bad Request
  [root@k8smaster01 helm-charts]#
  </code></pre>
  
  <p>my minio version is latest（RELEASE.2020-06-14T18-32-17Z） 
  my mc version is RELEASE.2020-05-28T23-43-36Z
  my helm version is version.BuildInfoVersion:"v3.2.3"</p>
  
  <p>how can i add the repo to helm successfully?</p>