You can do this already in Bitbucket Pipelines and your preferred PaaS provider -- just set up a manual step on your branch pipeline to deploy it. We built Deployments to help teams track changes in their _shared_ environments, which is where most of the value for tracking is.

Who would want to see a history of deployments for a branch-specific environment? What information would they be looking for?

In the early release, it's not possible: the 3 default environments are at the moment just for the repository, not per branch. You can deploy from multiple branches to the same environment though. Can you elaborate on why this would be helpful for you?

I was asking because we build a product that is deployed at customer site, so deployments would not be useful for that. But, we do deploy our own product to test environments for manual testing. (We also have automatic testing, but thats per commit and removed after testing... so not relevant here.)

We have the following branches (simplified): master release-4.2.x release-5.0.x release-5.1.x

Now, I was thinking to use the deployments feature to track the deployment of the test environment of each branch. So our testers can see the status of their test environment.

Branch-specific test environments would allow regression testing to happen _before_ changes get merged (I've used Travis to do this). I would love to have this kind of test isolation in our CI environment.