bugfix: remove duplicate error msgs

[faycheng]

Signed-off-by: 程飞 fay.cheng.cn@gmail.com

Ⅰ. Describe what this PR did

pouch daemon will print duplicate error messages if fails to create endpoint.
so, i remove duplicate output in func EndpointCreate.

ERRO[2018-04-03 20:40:33.310004469] failed to create endpoint, err: service endpoint with name 169a941d already exists
ERRO[2018-04-03 20:40:33.310011239] failed to create endpoint: service endpoint with name 169a941d already exists

Thanks a lot for your reviews and comments.

Ⅱ. Does this pull request fix one issue?

Ⅲ. Describe how you did it

Ⅳ. Describe how to verify it

Ⅴ. Special notes for reviews

[allencloud]

This removal LGTM, while I wish we could do a little more change:

how about
fmt.Errorf("failed to build sandbox options: %v", err) rather than
fmt.Errorf("failed to build sandbox options, err: %v", err)?

[faycheng]

got it

[faycheng]

done

[allencloud]

The log is already showed in https://github.com/alibaba/pouch/blob/master/daemon/mgr/container.go#L502

if _, err := mgr.NetworkMgr.EndpointCreate(ctx, endpoint); err != nil {
	logrus.Errorf("failed to create endpoint: %v", err)
	return err
}

So I think the removal is reasonable.
cc @rudyfly WDYT?

[allencloud]

LGTM