How to deploy ember-cli app to S3

I have an ember-cli app that is deployed in S3. It works well, and I have Travis set up to deploy changes when there is a merge into the master branch in GitHub.

But sometimes I want to test a change in the deployment environment without a commit -- perhaps because it can only be tested in that environment, like a fix to a mobile-only defect.

So I tried:

ember build --environment=production

followed by:

aws s3 cp dist/ s3://my_bucket/ --recursive

which uploaded things to my bucket. But the page didn't work, my browser told me there was a redirect loop. It wasn't a code issue, because when I pushed the changes to master, Travis successfully deployed them to S3.

Is there something clearly wrong with what I did, copying the dist folder to my bucket?