func setRequestContext(r *Request, ctx aws.Context) {
	r.context = ctx
	r.HTTPRequest = r.HTTPRequest.WithContext(ctx)
}
setContext updates the Request to use the passed in context for cancellation.
Context will also be used for request retry delay.

Creates shallow copy of the http.Request with the WithContext method.
package request
import "github.com/aws/aws-sdk-go/aws"